AWS Cloud9でHerokuにデプロイをすることができない

前提・実現したいこと

Rails Tutorial第1章の項目1.5デプロイするにおいて
hello,world!をデプロイしたいです。

発生している問題・エラーメッセージ

hello,world!と表示したいのですが下の画像が表示されてしまいます。

エラーメッセージ
git push heroku masterを実行した際に以下のエラーが発生します。

~/environment/hello_app (master) $ git push heroku master
Counting objects: 101, done.
Compressing objects: 100% (85/85), done.
Writing objects: 100% (101/101), 24.57 KiB | 1.44 MiB/s, done.
Total 101 (delta 4), 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: -----> Compiling Ruby/Rails
remote: -----> Using Ruby version: ruby-2.5.3
remote: -----> Installing dependencies using bundler 1.15.2
remote:        Running: bundle install --without development:test --path vendor/bundle --binstubs vendor/bundle/bin -j4 --deployment
remote:        Warning: the running version of Bundler (1.15.2) is older than the version that created the lockfile (1.16.6). We suggest you upgrade to the latest version of Bundler by running `gem install bundler`.
remote:        You are trying to install in deployment mode after changing
remote:        your Gemfile. Run `bundle install` elsewhere and add the
remote:        updated Gemfile.lock to version control.
remote:
remote:        The dependencies in your gemfile changed
remote:
remote:        You have added to the Gemfile:
remote:        * rails (= 5.1.6)
remote:        * puma (= 3.9.1)
remote:        * sass-rails (= 5.0.6)
remote:        * uglifier (= 3.2.0)
remote:        * coffee-rails (= 4.2.2)
remote:        * jquery-rails (= 4.3.1)
remote:        * turbolinks (= 5.0.1)
remote:        * jbuilder (= 2.6.4)
remote:        * sqlite3 (= 1.3.13)
remote:        * byebug (= 9.0.6)
remote:        * web-console (= 3.5.1)
remote:        * listen (= 3.1.5)
remote:        * spring (= 2.0.2)
remote:        * spring-watcher-listen (= 2.0.1)
remote:
remote:        You have deleted from the Gemfile:
remote:        * byebug
remote:        * capybara (~> 2.13)
remote:        * coffee-rails (~> 4.2)
remote:        * jbuilder (~> 2.5)
remote:        * listen (< 3.2, >= 3.0.5)
remote:        * puma (~> 3.7)
remote:        * rails (~> 5.1.6)
remote:        * sass-rails (~> 5.0)
remote:        * selenium-webdriver
remote:        * spring
remote:        * spring-watcher-listen (~> 2.0.0)
remote:        * sqlite3
remote:        * turbolinks (~> 5)
remote:        * uglifier (>= 1.3.0)
remote:        * web-console (>= 3.3.0)
remote:        Bundler Output: Warning: the running version of Bundler (1.15.2) is older than the version that created the lockfile (1.16.6). We suggest you upgrade to the latest version of Bundler by running `gem install bundler`.
remote:        You are trying to install in deployment mode after changing
remote:        your Gemfile. Run `bundle install` elsewhere and add the
remote:        updated Gemfile.lock to version control.
remote:
remote:        The dependencies in your gemfile changed
remote:
remote:        You have added to the Gemfile:
remote:        * rails (= 5.1.6)
remote:        * puma (= 3.9.1)
remote:        * sass-rails (= 5.0.6)
remote:        * uglifier (= 3.2.0)
remote:        * coffee-rails (= 4.2.2)
remote:        * jquery-rails (= 4.3.1)
remote:        * turbolinks (= 5.0.1)
remote:        * jbuilder (= 2.6.4)
remote:        * sqlite3 (= 1.3.13)
remote:        * byebug (= 9.0.6)
remote:        * web-console (= 3.5.1)
remote:        * listen (= 3.1.5)
remote:        * spring (= 2.0.2)
remote:        * spring-watcher-listen (= 2.0.1)
remote:
remote:        You have deleted from the Gemfile:
remote:        * byebug
remote:        * capybara (~> 2.13)
remote:        * coffee-rails (~> 4.2)
remote:        * jbuilder (~> 2.5)
remote:        * listen (< 3.2, >= 3.0.5)
remote:        * puma (~> 3.7)
remote:        * rails (~> 5.1.6)
remote:        * sass-rails (~> 5.0)
remote:        * selenium-webdriver
remote:        * spring
remote:        * spring-watcher-listen (~> 2.0.0)
remote:        * sqlite3
remote:        * turbolinks (~> 5)
remote:        * uglifier (>= 1.3.0)
remote:        * web-console (>= 3.3.0)
remote:
remote:  !
remote:  !     Failed to install gems via Bundler.
remote:  !
remote:  !     Push rejected, failed to compile Ruby app.
remote:
remote:  !     Push failed
remote: Verifying deploy...
remote: 
remote: !       Push rejected to whispering-meadow-74714.
remote: 
To https://git.heroku.com/whispering-meadow-74714remote: 
remote: !       Push rejected to whispering-meadow-74714.
remote: To https://git.heroku.com/whispering-meadow-74714.git
git
 ! [remote rejected] master -> master (pre-receive hook declined)error: failed to push some refs to 'https://git.heroku.com/whisperi

試したこと

teratailに掲載されている
Cloud9を利用したHerokuへのデプロイができない
を参考にしたのですが記事にて指摘されているGemfileの修正もtutorial通りに行なっているためどこを修正すれば良いのか検討がついてない状態におります。
※gemfileの内容は以下の通りです。

source 'https://rubygems.org'

gem 'rails',        '5.1.6'
gem 'puma',         '3.9.1'
gem 'sass-rails',   '5.0.6'
gem 'uglifier',     '3.2.0'
gem 'coffee-rails', '4.2.2'
gem 'jquery-rails', '4.3.1'
gem 'turbolinks',   '5.0.1'
gem 'jbuilder',     '2.7.0'

group :development, :test do
  gem 'sqlite3', '1.3.13'
  gem 'byebug',  '9.0.6', platform: :mri
end

group :development do
  gem 'web-console',           '3.5.1'
  gem 'listen',                '3.1.5'
  gem 'spring',                '2.0.2'
  gem 'spring-watcher-listen', '2.0.1'
end

group :production do
  gem 'pg', '0.20.0'
end

# Windows環境ではtzinfo-dataというgemを含める必要があります
gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]

ここに問題に対して試したことを記載してください。