Herokuにデプロイできない

Herokuにデプロイしようと色々試しているのですが何度試してもPrecompiling assets failed.というエラーが出て成功しません。
自分の知識不足なのかもしれないのですがいろいろ調べても解決方法が出てこず困っています。

下記がエラー内容です。

git push heroku master
Enumerating objects: 250, done.
Counting objects: 100% (250/250), done.
Delta compression using up to 8 threads
Compressing objects: 100% (224/224), done.
Writing objects: 100% (250/250), 425.44 KiB | 5.25 MiB/s, done.
Total 250 (delta 30), reused 0 (delta 0)
remote: Compressing source files... done.
remote: Building source:
remote: 
remote:  !     Warning: Multiple default buildpacks reported the ability to handle this app. The first buildpack in the list below will be used.
remote:                         Detected buildpacks: Ruby,Node.js
remote:                         See https://devcenter.heroku.com/articles/buildpacks#buildpack-detect-order
remote: -----> Ruby app detected
remote: -----> Installing bundler 2.0.2
remote: -----> Removing BUNDLED WITH version in the Gemfile.lock
remote: -----> Compiling Ruby/Rails
remote: -----> Using Ruby version: ruby-2.6.6
remote: 
remote: ###### WARNING:
remote: 
remote:        Removing `Gemfile.lock` because it was generated on Windows.
remote:        Bundler will do a full resolve so native gems are handled properly.
remote:        This may result in unexpected gem versions being used in your app.
remote:        In rare occasions Bundler may not be able to resolve your dependencies at all.
remote:        https://devcenter.heroku.com/articles/bundler-windows-gemfile
remote: 
remote: -----> Installing dependencies using bundler 2.0.2
remote:        Running: bundle install --without development:test --path vendor/bundle --binstubs vendor/bundle/bin -j4
remote:        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`.
remote:        Fetching gem metadata from https://rubygems.org/.............
remote:        Fetching gem metadata from https://rubygems.org/.
remote:        Resolving dependencies......
remote:        Fetching rake 13.0.1
####省略####
remote:        Fetching activesupport 5.1.7
remote:        Installing activesupport 5.1.7
remote:        Fetching sass-listen 4.0.0
remote:        Installing sass-listen 4.0.0
remote:        Fetching globalid 0.4.2
remote:        Installing globalid 0.4.2
remote:        Fetching activemodel 5.1.7
remote:        Installing activemodel 5.1.7
remote:        Fetching jbuilder 2.10.0
remote:        Installing jbuilder 2.10.0
remote:        Fetching sass 3.7.4
remote:        Installing sass 3.7.4
remote:        Fetching activejob 5.1.7
remote:        Installing activejob 5.1.7
remote:        Fetching activerecord 5.1.7
remote:        Installing activerecord 5.1.7
remote:        Fetching carrierwave 1.2.2
remote:        Installing carrierwave 1.2.2
remote:        Fetching rails-dom-testing 2.0.3
remote:        Fetching loofah 2.5.0
remote:        Installing rails-dom-testing 2.0.3
remote:        Installing loofah 2.5.0
remote:        Fetching impressionist 1.6.1
remote:        Fetching rails-html-sanitizer 1.3.0
remote:        Installing impressionist 1.6.1
remote:        Installing rails-html-sanitizer 1.3.0
remote:        Fetching actionview 5.1.7
remote:        Installing actionview 5.1.7
remote:        Fetching actionpack 5.1.7
remote:        Installing actionpack 5.1.7
remote:        Fetching actionmailer 5.1.7
remote:        Fetching actioncable 5.1.7
remote:        Fetching railties 5.1.7
remote:        Installing actionmailer 5.1.7
remote:        Installing actioncable 5.1.7
remote:        Installing railties 5.1.7
remote:        Fetching sprockets-rails 3.2.1
remote:        Installing sprockets-rails 3.2.1
remote:        Fetching coffee-rails 4.2.2
remote:        Fetching rails 5.1.7
remote:        Fetching sass-rails 5.0.7
remote:        Installing rails 5.1.7
remote:        Installing coffee-rails 4.2.2
remote:        Installing sass-rails 5.0.7
remote:        Bundle complete! 18 Gemfile dependencies, 61 gems now installed.
remote:        Gems in the groups development and test were not installed.
remote:        Bundled gems are installed into `./vendor/bundle`
remote:        Post-install message from i18n:
remote:        
remote:        HEADS UP! i18n 1.1 changed fallbacks to exclude default locale.
remote:        But that may break your application.
remote:        
remote:        If you are upgrading your Rails application from an older version of Rails:
remote:        
remote:        Please check your Rails app for 'config.i18n.fallbacks = true'.
remote:        If you're using I18n (>= 1.1.0) and Rails (< 5.2.2), this should be
remote:        'config.i18n.fallbacks = [I18n.default_locale]'.
remote:        If not, fallbacks will be broken in your app by I18n 1.1.x.
remote:        
remote:        If you are starting a NEW Rails application, you can ignore this notice.
remote:        
remote:        For more info see:
remote:        https://github.com/svenfuchs/i18n/releases/tag/v1.1.0
remote:        
remote:        Post-install message from sass:
remote:        
remote:        Ruby Sass has reached end-of-life and should no longer be used.
remote:        
remote:        * If you use Sass as a command-line tool, we recommend using Dart Sass, the new
remote:          primary implementation: https://sass-lang.com/install
remote:        
remote:        * If you use Sass as a plug-in for a Ruby web framework, we recommend using the
remote:          sassc gem: https://github.com/sass/sassc-ruby#readme
remote:        
remote:        * For more details, please refer to the Sass blog:
remote:          https://sass-lang.com/blog/posts/7828841
remote:        
remote:        Bundle completed (39.36s)
remote:        Cleaning up the bundler cache.
remote: -----> Installing node-v10.15.3-linux-x64
remote: -----> Detecting rake tasks
remote: -----> Preparing app for Rails asset pipeline
remote:        Running: rake assets:precompile
remote:        Yarn executable was not detected in the system.
remote:        Download Yarn at https://yarnpkg.com/en/docs/install
remote:        I, [2020-05-10T15:21:47.626514 #1220]  INFO -- : Writing /tmp/build_da4e11739166d880f1c79d5517c13d26/public/assets/default_profile_banner-e79ecf3ec09f33ccee6814348e37f651df15936a2cf0a0b669ccbe7a4aa8707a.png
####省略####
remote:        rake aborted!
remote:        Sass::SyntaxError: File to import not found or unreadable: style.
remote:        (sass):1
remote:        /tmp/build_da4e11739166d880f1c79d5517c13d26/vendor/bundle/ruby/2.6.0/gems/sass-3.7.4/lib/sass/tree/import_node.rb:67:in `rescue in import'
remote:        /tmp/build_da4e11739166d880f1c79d5517c13d26/vendor/bundle/ruby/2.6.0/gems/sass-
####省略####
remote:        
remote:        Caused by:
remote:        Sass::SyntaxError: File to import not found or unreadable: style.
remote:        /tmp/build_da4e11739166d880f1c79d5517c13d26/vendor/bundle/ruby/2.6.0/gems/sass-3.7.4/lib/sass/tree/import_node.rb:65:in `import'
####省略####
remote:        /tmp/build_da4e11739166d880f1c79d5517c13d26/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/exe/rake:27:in `<top (required)>'
remote:        Tasks: TOP => assets:precompile
remote:        (See full trace by running task with --trace)
remote:        zlib(finalizer): Zlib::GzipWriter object must be closed explicitly.
remote:        zlib(finalizer): the stream was freed prematurely.
remote: 
remote:  !
remote:  !     Precompiling assets failed.
remote:  !
remote:  !     Push rejected, failed to compile Ruby app.
remote: 
remote:  !     Push failed
remote: Verifying deploy...
remote: 
remote: !       Push rejected to App.
remote: 
To https://git.heroku.com/App.git
 ! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to 'https://git.heroku.com/App.git'