Add Rails 7.0 and Ruby 3.1 to build matrix

[pirj]

https://www.ruby-lang.org/en/news/2021/12/25/ruby-3-1-0-released/
https://rubyonrails.org/2021/12/15/Rails-7-fulfilling-a-vision

[andrehjr]

Hi 🙌

You should use '3.0' otherwise github actions will pull 3.1. Related to this actions/runner#849 / ruby/setup-ruby#252

I guess, all other ruby versions should be quoted too? 🤔

[pirj]

Thanks for noticing!
I guess only x.0 versions are affected.

[pirj]

Job failures are unrelated, will fix in a follow-up. rubygems are out of date. We've removed update_rubygems_and_install_bundler step when migrated from Travis to GHA:

     Failure/Error: expect(`bundle exec #{script} 2>&1`).to be_empty
       expected `"Your RubyGems version (2.7.6.3)) has a bug that prevents `required_ruby_version` from working for Bundler. Any scripts that use `gem install bundler` will break as soon as Bundler drops support for your Ruby version. Please upgrade RubyGems to avoid future breakage and silence this warning by running `gem update --system 3.2.3`\n".empty?` to be truthy, got false

      Failure/Error: expect(`bundle exec #{script} 2>&1`).to be_empty
       expected `"Your RubyGems version (2.6.14.4)) has a bug that prevents `required_ruby_version` from working for Bundler. Any scripts that use `gem install bundler` will break as soon as Bundler drops support for your Ruby version. Please upgrade RubyGems to avoid future breakage and silence this warning by running `gem update --system 3.2.3`\n".empty?` to be truthy, got false
     # /home/runner/work/rspec-rails/rspec-support/lib/rspec/support.rb:102:in `block in <module:Support>'

      Failure/Error: expect(`bundle exec #{script} 2>&1`).to be_empty
       expected `"Your RubyGems version (2.7.6.2)) has a bug that prevents `required_ruby_version` from working for Bundler. Any scripts that use `gem install bundler` will break as soon as Bundler drops support for your Ruby version. Please upgrade RubyGems to avoid future breakage and silence this warning by running `gem update --system 3.2.3`\n".empty?` to be truthy, got false

      Failure/Error: expect(`bundle exec #{script} 2>&1`).to be_empty
       expected `"Your RubyGems version (2.5.2.3)) has a bug that prevents `required_ruby_version` from working for Bundler. Any scripts that use `gem install bundler` will break as soon as Bundler drops support for your Ruby version. Please upgrade RubyGems to avoid future breakage and silence this warning by running `gem update --system 3.2.3`\n".empty?` to be truthy, got false