This update for libmodulemd fixes the following issues:

libmodulemd was updated to 2.12.1:

- This is a bug-fix release fully compatible with the previous 2.12.0
version.

Notable changes:

Enhancements:

- Improve diagnostic messages for compression tests.
- Tests performed in a GitHub continues integration are faster.
- Use GitHub actions to perform CI tests also on ArchLinux, Mageia,
Mandriva, and OpenSUSE.

Fixes:

- Relax context value up to 13 characters including an underscore
character in modulemd v2 format. This reenables scratch-builds in MBS.
Migrate Packit tests from a deprecated current_version_command to
a newer actions/get-current-version.