Run Github Actions on Debian

[prandla]

• Refactored the Dockerfile to allow building both Debian- and Ubuntu-based images from the same file.
• Various other cleanups in the dockerfile:
  • Use cache mounts to avoid re-downloading packages when rebuilding. Note that this is not the same type of caching I tried in a previous PR, in particular this one doesn't help with CI at all, but it helps a lot locally to speed up rebuilds when tinkering with the dockerfile.
  • made the shell commands a bit cleaner using heredoc syntax.
  • use the correct isolate repository for the current distro, instead of hardcoding bookworm
  • tweaked the installed package list a bit for debian, see the commit message for details. Notably, upgrade java from version 8 to 17 or 21 (debian only packages one version of java).

One test actually broke on debian because of python 3.11, because of changes in zipfile.py in python 3.12 which I inadvertently depended on (namely the "archive with empty filename" test). I don't think either behavior is a problem though, it shouldn't really matter which way this edge case is resolved, the user will get an error message either way in the end.

And finally, run the CI with both ubuntu and debian images. We'll see if it works first try :)

[veluca93]

Please wait until EOW :-)

[prandla]

hmm, it shows that CI passed on both "test (debian)" and "test (ubuntu)", but it's still waiting for "test". I guess this is due to some weirdness with the branch protection rules? But I don't have permissions to look at those, so someone else will have to tinker with them...