Matching by managers was missing "gitlabci" since 1ccd7042. This
should be less fragile.

This confused renovate, see !17

Cf. !13
Cf. https://github.com/rails/tailwindcss-rails?tab=readme-ov-file#upgrading-your-application-from-tailwind-v3-to-v4

For some reason, the package is called "ruby-version"?

The dockerfileVersions rule uses the regex manager. I hope?