Remove ruby find_program and ronn. Not really used

[j-rivero]

🦟 Issue fix

Summary

The build process is not using ruby or ruby-ronn at all. Remove it from CMake.

Checklist

• [x] Signed all commits for DCO

Note to maintainers: Remember to use Squash-Merge

[j-rivero]

LGTM, I think we can also remove ruby-ronn from the README?

done! thanks.