Updated: rubygems 3.4.12

[Daisuke Fujimura via Cygwin-announce]

The following packages have been uploaded to the Cygwin distribution:

* rubygems
* rubygems-doc

Package summary
* https://cygwin.com/packages/summary/rubygems-src.html

Changelog
* https://github.com/rubygems/rubygems/blob/v3.4.12/CHANGELOG.md