CircleCIからHerokuにデプロイできない

前提・実現したいこと

RailsアプリをCircleCIでテストを行なった上でmasterブランチに上がったものを自動デプロイしたいと思っております。
開発用ブランチdevでのテストはSUCCESSが出ました。
DBサーバーはpostgresで，環境変数等の設定も行なっております。

発生している問題・エラーメッセージ

masterからgit pushをcircleciから行う時，次のようなエラーが出て停止しました。（CircleCIの画面）
初心者ゆえにどうすればわからないもので，よろしくお願いします。

（中略）
remote:        Asset precompilation completed (50.31s)        
remote:        Cleaning assets        
remote:        Running: rake assets:clean        
remote: -----> Detecting rails configuration        
remote: 
remote: ###### WARNING:        
remote: 
remote:        You set your `config.assets.compile = true` in production.        
remote:        This can negatively impact the performance of your application.        
remote:                
remote:        For more information can be found in this article:        
remote:          https://devcenter.heroku.com/articles/rails-asset-pipeline#compile-set-to-true-in-production        
remote:                
remote: 
remote: ###### WARNING:        
remote: 
remote:        You set your `config.active_storage.service` to :local in production.        
remote:        If you are uploading files to this app, they will not persist after the app        
remote:        is restarted, on one-off dynos, or if the app has multiple dynos.        
remote:        Heroku applications have an ephemeral file system. To        
remote:        persist uploaded files, please use a service such as S3 and update your Rails        
remote:        configuration.        
remote:                
remote:        For more information can be found in this article:        
remote:          https://devcenter.heroku.com/articles/active-storage-on-heroku        
remote:                
remote: 
remote: ###### WARNING:        
remote: 
remote:        We detected that some binary dependencies required to        
remote:        use all the preview features of Active Storage are not        
remote:        present on this system.        
remote:                
remote:        For more information please see:        
remote:          https://devcenter.heroku.com/articles/active-storage-on-heroku        
remote:                
remote: 
remote: ###### WARNING:        
remote: 
remote:        There is a more recent Ruby version available for you to use:        
remote:                
remote:        2.6.6        
remote:                
remote:        The latest version will include security and bug fixes, we always recommend        
remote:        running the latest version of your minor release.        
remote:                
remote:        Please upgrade your Ruby version.        
remote:                
remote:        For all available Ruby versions see:        
remote:          https://devcenter.heroku.com/articles/ruby-support#supported-runtimes        
remote: 
remote: ###### WARNING:        
remote: 
remote:        No Procfile detected, using the default web server.        
remote:        We recommend explicitly declaring how to boot your server process via a Procfile.        
remote:        https://devcenter.heroku.com/articles/ruby-default-web-server        
remote: 
remote: 
remote: -----> Rake app detected        
remote: D, [2020-04-05T05:21:04.462876 #628] DEBUG -- :    (1.5ms)  SELECT pg_try_advisory_lock(2295715680445278420)        
remote: D, [2020-04-05T05:21:04.497100 #628] DEBUG -- :    (4.9ms)  SELECT "schema_migrations"."version" FROM "schema_migrations" ORDER BY "schema_migrations"."version" ASC        
remote: I, [2020-04-05T05:21:04.497660 #628]  INFO -- : Migrating to Mqrshop (20200404124900)        
remote: == 20200404124900 Mqrshop: migrating ==========================================        
remote: -- add_column(:makeqrs, :store, :string)        
remote: D, [2020-04-05T05:21:04.501512 #628] DEBUG -- :    (1.0ms)  BEGIN        
remote: D, [2020-04-05T05:21:04.521396 #628] DEBUG -- :    (19.8ms)  ALTER TABLE "makeqrs" ADD "store" character varying        
remote:    -> 0.0213s        
remote: == 20200404124900 Mqrshop: migrated (0.0213s) =================================        
remote: 
remote: D, [2020-04-05T05:21:04.529296 #628] DEBUG -- :   primary::SchemaMigration Create (1.7ms)  INSERT INTO "schema_migrations" ("version") VALUES ($1) RETURNING "version"  [["version", "20200404124900"]]        
remote: D, [2020-04-05T05:21:04.541502 #628] DEBUG -- :    (12.0ms)  COMMIT        
remote: D, [2020-04-05T05:21:04.552649 #628] DEBUG -- :   ActiveRecord::InternalMetadata Load (3.7ms)  SELECT "ar_internal_metadata".* FROM "ar_internal_metadata" WHERE "ar_internal_metadata"."key" = $1 LIMIT $2  [["key", "environment"], ["LIMIT", 1]]        
remote: D, [2020-04-05T05:21:04.559694 #628] DEBUG -- :    (1.1ms)  SELECT pg_advisory_unlock(2295715680445278420)        
remote: rake aborted!        
remote: Don't know how to build task 'cache:clear' (See the list of available tasks with `rake --tasks`)        
remote: /tmp/build_e8ef12279516b19492c568a619132e0c/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/exe/rake:27:in `<top (required)>'        
remote: (See full trace by running task with --trace)        
remote:  !     Push rejected, failed to compile Rake app.        
remote: 
remote:  !     Push failed        
remote: Verifying deploy...
remote: 
remote: !	Push rejected to ************.        
remote: 
To https://git.heroku.com/************.git
 ! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to 'https://heroku:************************************@git.heroku.com/************.git'

Exited with code exit status 1
CircleCI received exit code 1

該当のソースコード

config.yml

circleci
1version: 2.1
2orbs:
3  # https://circleci.com/orbs/registry/orb/circleci/heroku
4  heroku: circleci/heroku@0.0.4
5references:
6  default_docker_ruby_executor: &default_docker_ruby_executor
7    image: circleci/ruby:2.6.5-stretch-node
8    environment:
9      BUNDLE_JOBS: 3
10      BUNDLE_RETRY: 3
11      BUNDLE_PATH: vendor/bundle
12      PGHOST: 127.0.0.1
13      PGUSER: （postgresのユーザ名）
14      PGPASSWORD: "（postgresのパスワード）"
15      RAILS_ENV: test
16  postgres: &postgres
17    image: circleci/postgres:9.5-alpine
18    environment:
19      POSTGRES_USER: （postgresのユーザ名）
20      POSTGRES_DB: （postgresのDB名）
21      POSTGRES_PASSWORD: "（postgresのパスワード）"
22
23jobs:
24  build:
25    docker:
26      - *default_docker_ruby_executor
27    steps:
28      - checkout
29      # Which version of bundler?
30      - run:
31          name: Install particular bundler2.1.4
32          command: gem install bundler:2.1.4
33      - run:
34          name: Bundle Install
35          command: bundle check || bundle install
36      # Store bundle cache
37      - save_cache:
38          key: rails-demo-bundle-v2-{{ checksum "Gemfile.lock" }}
39          paths:
40            - vendor/bundle
41      # Only necessary if app uses webpacker or yarn in some other way
42      - restore_cache:
43          keys:
44            - rails-demo-yarn-{{ checksum "yarn.lock" }}
45            - rails-demo-yarn-
46      - run:
47          name: Yarn Install
48          command: yarn install --cache-folder ~/.cache/yarn
49      # Store yarn / webpacker cache
50      - save_cache:
51          key: rails-demo-yarn-{{ checksum "yarn.lock" }}
52          paths:
53            - ~/.cache/yarn
54  test:
55    parallelism: 1
56    docker:
57      - *default_docker_ruby_executor
58      - *postgres
59    steps:
60      - checkout
61      - restore_cache:
62          keys:
63            - rails-demo-bundle-v2-{{ checksum "Gemfile.lock" }}
64            - rails-demo-bundle-v2-
65      - run:
66          name: Install particular bundler2.1.4
67          command: gem install bundler:2.1.4
68      - run:
69          name: Bundle Install
70          command: bundle check || bundle install
71      - restore_cache:
72          keys:
73            - rails-demo-yarn-{{ checksum "yarn.lock" }}
74            - rails-demo-yarn-
75      - run:
76          name: Wait for DB
77          command: dockerize -wait tcp://localhost:5432 -timeout 1m
78      - run:
79          name: Database setup
80          command: bundle exec rails db:schema:load --trace
81      # Run rspec in parallel
82      - run:
83          command: |
84            mkdir /tmp/test-results
85            TESTFILES=$(circleci tests glob "spec/**/*_spec.rb" | circleci tests split --split-by=timings)
86            bundle exec rspec $TESTFILES --profile 10 --format RspecJunitFormatter --out /tmp/test-results/rspec.xml --format progress
87      - store_test_results:
88          path: /tmp/test-results
89      - store_artifacts:
90          path: /tmp/test-results
91          destination: test-results
92  deploy:
93      executor: heroku/default
94      steps:
95        - checkout
96        - heroku/install
97        - heroku/deploy-via-git
98
99
100
101workflows:
102  version: 2
103  build-deploy:
104    jobs:
105      - build
106      - test:
107          requires:
108            - build
109      - deploy:
110          requires:
111            - build
112          filters:
113              branches:
114                only: master