www/gitlab-ce: major update to 15.0.0

Changelog:
https://about.gitlab.com/releases/2022/05/22/gitlab-15-0-released/

This commit also includes a not so strict restriction on rails61.
This is not tested by gitlab itself, but my tests showed that it should work.
This fixes a regression introduced by:
2dd5a4751e19c9a02911d797d67fff6ec9f09da4

PR: 263688