ghcup-metadata: More metadata fixes

• Incorrect version range on the alpine bindists
• Missing underscore in "unknown_versioning"

Fixes #25119 (closed)

mentioned in issue #25119 (closed)

approved this merge request

assigned to @marge-bot

I will attempt to batch this MR (!13080 (closed))...

Batch MR !13080 (closed) failed: CI failed! I will retry later...

I will attempt to batch this MR (!13082 (closed))...

Merged in e258ad54

closed