enhancement: check pkgrel validity automatically in CI

See ollieparanoid's comment here:

On the Wiki, there's a set of guidelines on when pkgrel in APKBUILD should be increased, and how pkgrel should be set to zero for newly added aports.

Would it be possible to automatically check these guidelines in a CI testcase, so developers would automatically get a notification if they need to increment or change the pkgrel in their merge request?