Ruby on Rails 6.0

[Pavel Valena]

Hello,

Ruby on Rails 6.0 has just landed in F33 and Rawhide:
  https://fedoraproject.org/wiki/Changes/Ruby_on_Rails_6.0

Updates:
  https://bodhi.fedoraproject.org/updates/FEDORA-2020-5bc381f3f0
  https://bodhi.fedoraproject.org/updates/FEDORA-2020-aaf2c426af

Can be installed / run / tested like so:
  https://gist.github.com/pvalena/0cc2cfa7700238c7a048f60aab3e8e30
  https://gist.github.com/pvalena/9899e8e998dc284273b55af7f7f7c887

I've also added / prepared test (preparing for CI) to tests namespace:
  https://src.fedoraproject.org/tests/ruby/pull-request/1/#comment-53969

Railties and ActiveStorage testsuites are still disabled, but'll fix+enable those soon.

Let me know if you run into any issues!