git push heroku masterを行うとNameError: uninitialized constant Deviseと出てくる

*解決したいこと
git push heroku masterを行うとNameError: uninitialized constant Deviseと出てくるのを解決したいです。

*前提
現在railsでwebアプリを開発していてherokuにデプロイをしようとしている段階です。

*出てくるエラー
git push heroku masterとコマンドを叩くと以下のようなエラーが出ます。

remote:        Running: rake assets:precompile
remote:        rake aborted!
remote:        NameError: uninitialized constant Devise

*試したこと
元々deviseは入れていたのですが使わない方針に変えたのでgemfileから消したのですが、エラーは解決しませんでした。

Gemfile
1source 'https://rubygems.org'
2git_source(:github) { |repo| "https://github.com/#{repo}.git" }
3
4ruby '2.6.3'
5
6# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
7gem 'rails', '~> 5.2.3'
8gem 'will_paginate', '3.1.7'
9gem 'carrierwave'
10gem 'rmagick'
11gem 'mini_magick'
12gem 'bootstrap-will_paginate', '1.0.0'
13gem 'bootstrap-sass', '3.3.7'
14# Use sqlite3 as the database for Active Record
15# gem 'sqlite3'
16# Use Puma as the app server
17gem 'puma', '~> 3.11'
18# Use SCSS for stylesheets
19gem 'sass-rails', '~> 5.0'
20# Use Uglifier as compressor for JavaScript assets
21gem 'uglifier', '>= 1.3.0'
22# See https://github.com/rails/execjs#readme for more supported runtimes
23# gem 'mini_racer', platforms: :ruby
24
25# Use CoffeeScript for .coffee assets and views
26gem 'coffee-rails', '~> 4.2'
27# Turbolinks makes navigating your web application faster. Read more: https://github.com/turbolinks/turbolinks
28gem 'turbolinks', '~> 5'
29# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
30gem 'jbuilder', '~> 2.5'
31# Use Redis adapter to run Action Cable in production
32# gem 'redis', '~> 4.0'
33# Use ActiveModel has_secure_password
34# gem 'bcrypt', '~> 3.1.7'
35
36# Use ActiveStorage variant
37# gem 'mini_magick', '~> 4.8'
38
39# Use Capistrano for deployment
40# gem 'capistrano-rails', group: :development
41
42# Reduces boot times through caching; required in config/boot.rb
43gem 'bootsnap', '>= 1.1.0', require: false
44
45group :production do
46  gem 'pg', '0.20.0'
47end
48
49group :development, :test do
50  # Call 'byebug' anywhere in the code to stop execution and get a debugger console
51  gem 'sqlite3', '1.3.13'
52  gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]
53  gem 'rspec-rails', '~>3.6.0'
54  gem 'factory_bot_rails', '~>4.10.0'
55  gem 'database_cleaner'
56  gem 'pry-rails'
57  gem 'pry-byebug'
58  gem 'pry-doc'
59end
60
61group :development do
62  # Access an interactive console on exception pages or by calling 'console' anywhere in the code.
63  gem 'web-console', '>= 3.3.0'
64  gem 'listen', '>= 3.0.5', '< 3.2'
65  # Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring
66  gem 'spring'
67  gem 'spring-watcher-listen', '~> 2.0.0'
68  gem 'spring-commands-rspec'
69end
70
71group :test do
72  # Adds support for Capybara system testing and selenium driver
73  gem 'capybara', '>= 2.15'
74  gem 'selenium-webdriver'
75  # Easy installation and use of chromedriver to run system tests with Chrome
76  gem 'chromedriver-helper'
77end
78
79# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
80gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]
81
82gem 'coffee-script-source', '1.8.0'
83gem 'bcrypt', '3.1.12'
84gem 'rails-controller-testing'
85gem 'slim-rails'
86gem 'html2slim'

bundle info deviseとコマンドを叩くと以下のような表示が出ることも確認済みです。

$ bundle info devise
The dependency tzinfo-data (>= 0) will be unused by any of the platforms Bundler is installing for. Bundler is installing for ruby but the dependency is only for x86-mingw32, x86-mswin32, x64-mingw32, java. To add those platforms to the bundle, run `bundle lock --add-platform x86-mingw32
 x86-mswin32 x64-mingw32 java`.
Could not find gem 'devise'.

＊環境
rails 5.2

以上、もし分かる方いらっしゃいましたら、ご回答よろしくお願いします。