Fix for grml filename changes

[Seth Arnold]

Hello, grml ISOs have had a filename change that means new versions aren't available on 24.04 LTS: https://github.com/grml/grml-rescueboot/issues/28#issuecomment-2849355924

This update on Debian addressed the issue: https://tracker.debian.org/news/1601155/accepted-grml-rescueboot-052deb12u1-source-into-proposed-updates/

I believe it would require backporting these commits to fix it in our 24.04 LTS packages:

- https://github.com/grml/grml-rescueboot/commit/8a4f714fabe96c66b000c604c0a264ec7a68565b
- https://github.com/grml/grml-rescueboot/commit/dc09c7273f67f51be43f8d531ff19ec0983d93fa
- https://github.com/grml/grml-rescueboot/commit/66655b231df64956b2603b8b36ff019aef29e63c
- https://github.com/grml/grml-rescueboot/commit/d833bb9d2323c8e543e17330d88c9d019abf8392

Thanks

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.