Ruby 2.7 change proposal

Hi Rubyists, The release of Ruby 2.7 is coming close and to be ready for rebuild after Christmas, I have submitted the Ruby 2.7 change proposal [1]. It is already in `ChangeReadyForWrangler` state, since I don't expect any controversy. But anyway, please review and let me know if you have any concerns. Vít [1] https://fedoraproject.org/wiki/Changes/Ruby_2.7