App won't deploy successfully

Logs:
$ git push heroku master
Enumerating objects: 983, done.
Counting objects: 100% (983/983), done.
Delta compression using up to 8 threads
Compressing objects: 100% (432/432), done.
Writing objects: 100% (983/983), 842.94 KiB | 140.49 MiB/s, done.
Total 983 (delta 528), reused 983 (delta 528)
remote: Compressing source files... done.
remote: Building source:
remote:
remote: -----> Ruby app detected
remote: -----> Compiling Ruby/Rack
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: fatal: not a git repository (or any parent up to mount point /)
remote: Stopping at filesystem boundary (GIT_DISCOVERY_ACROSS_FILESYSTEM not set).
remote: Fetching gem metadata from https://rubygems.org/........
remote: Fetching version metadata from https://rubygems.org/..
remote: Fetching dependency metadata from https://rubygems.org/.
remote: Fetching i18n 0.8.0
remote: Fetching minitest 4.7.5
remote: Fetching multi_json 1.12.1
remote: Installing multi_json 1.12.1
remote: Installing minitest 4.7.5
remote: Installing i18n 0.8.0
remote: Fetching thread_safe 0.3.5
remote: Fetching tzinfo 0.3.52
remote: Installing thread_safe 0.3.5
remote: Installing tzinfo 0.3.52
remote: Fetching bson 4.2.1
remote: Installing bson 4.2.1 with native extensions
remote: Fetching bson_ext 1.5.1
remote: Installing bson_ext 1.5.1 with native extensions
remote: Using bundler 1.15.2
remote: Fetching chronic 0.10.2
remote: Installing chronic 0.10.2
remote: Fetching numerizer 0.1.1
remote: Installing numerizer 0.1.1
remote: Fetching cinch 2.3.3
remote: Installing cinch 2.3.3
remote: Fetching concurrent-ruby 1.0.4
remote: Installing concurrent-ruby 1.0.4
remote: Fetching configatron 4.5.0
remote: Installing configatron 4.5.0
remote: Fetching daemons 1.2.4
remote: Installing daemons 1.2.4
remote: Fetching unf_ext 0.0.7.2
remote: Installing unf_ext 0.0.7.2 with native extensions
remote: Fetching eventmachine 1.2.2
remote: Installing eventmachine 1.2.2 with native extensions
remote: Fetching multipart-post 2.0.0
remote: Installing multipart-post 2.0.0
remote: Fetching websocket-extensions 0.1.2
remote: Installing websocket-extensions 0.1.2
remote: Fetching gli 2.15.0
remote: Installing gli 2.15.0
remote: Fetching hashie 3.5.1
remote: Installing hashie 3.5.1
remote: Fetching json 2.0.3
remote: Installing json 2.0.3 with native extensions
remote: Fetching mime-types-data 3.2016.0521
remote: Installing mime-types-data 3.2016.0521
remote: Fetching netrc 0.11.0
remote: Installing netrc 0.11.0
remote: Fetching method_decorators 0.9.6
remote: Installing method_decorators 0.9.6
remote: Fetching rack 1.6.5
remote: Installing rack 1.6.5
remote: Fetching tilt 2.0.6
remote: Installing tilt 2.0.6
remote: Fetching activesupport 4.0.13
remote: Installing activesupport 4.0.13
remote: Fetching chronic_duration 0.10.6
remote: Installing chronic_duration 0.10.6
remote: Fetching semantic_logger 3.4.1
remote: Installing semantic_logger 3.4.1
remote: Fetching mongo 2.4.1
remote: Installing mongo 2.4.1
remote: Fetching faraday 0.11.0
remote: Installing faraday 0.11.0
remote: Fetching websocket-driver 0.6.5
remote: Installing websocket-driver 0.6.5 with native extensions
remote: Fetching unf 0.1.4
remote: Installing unf 0.1.4
remote: Fetching mime-types 3.1
remote: Installing mime-types 3.1
remote: Fetching rack-protection 1.5.3
remote: Installing rack-protection 1.5.3
remote: Fetching faraday_middleware 0.11.0.1
remote: Installing faraday_middleware 0.11.0.1
remote: Fetching domain_name 0.5.20161129
remote: Installing domain_name 0.5.20161129
remote: Fetching sinatra 1.4.8
remote: Installing sinatra 1.4.8
remote: Fetching http-cookie 1.0.3
remote: Installing http-cookie 1.0.3
remote: Fetching rest-client 2.0.0
remote: Installing rest-client 2.0.0
remote: Fetching mailgun-ruby 1.1.2
remote: Installing mailgun-ruby 1.1.2
remote: Fetching faye-websocket 0.10.6
remote: Fetching thin 1.7.0
remote: Installing thin 1.7.0 with native extensions
remote: Installing faye-websocket 0.10.6
remote: Fetching slack-ruby-client 0.7.9
remote: Installing slack-ruby-client 0.7.9
remote: Using pagerbot 0.3.0 from source at `.`
remote: Bundle complete! 9 Gemfile dependencies, 45 gems now installed.
remote: Gems in the groups development and test were not installed.
remote: Bundled gems are installed into ./vendor/bundle.
remote: Bundle completed (32.88s)
remote: Cleaning up the bundler cache.
remote: -----> Detecting rake tasks
remote: Could not detect rake tasks
remote: ensure you can run `$ bundle exec rake -P` against your app
remote: and using the production group of your Gemfile.
remote: /tmp/build_516621b0dcb6ff90cc1e17d94c4bc75e/vendor/ruby-2.5.3/lib/ruby/2.5.0/rubygems.rb:284:in `find_spec_for_exe': can't find gem rake (>= 0.a) with executable rake (Gem::GemNotFoundException)
remote: from /tmp/build_516621b0dcb6ff90cc1e17d94c4bc75e/vendor/ruby-2.5.3/lib/ruby/2.5.0/rubygems.rb:303:in `activate_bin_path'
remote: from /tmp/build_516621b0dcb6ff90cc1e17d94c4bc75e/vendor/ruby-2.5.3/bin/rake:29:in `<main>'
remote:
remote: ###### WARNING:
remote:
remote: You have not declared a Ruby version in your Gemfile.
remote: To set your Ruby version add this line to your Gemfile:
remote: ruby '2.5.3'
remote: # See https://devcenter.heroku.com/articles/ruby-versions for more information.
remote:
remote:
remote: -----> Discovering process types
remote: Procfile declares types -> bot, web
remote: Default types for buildpack -> console, rake
remote:
remote: -----> Compressing...
remote: Done: 21.3M
remote: -----> Launching...
remote: Released v8
remote: https://tranquil-stream-69081.herokuapp.com/ deployed to Heroku
remote:
remote: Verifying deploy... done.