community/b4: move from testing, rebuild against Python 3.12

Supersedes !64258 (closed) and part of !64350 (closed).

Moves py3-patatt, py3-dkimpy, py3-authres, git-filter-repo (needs ack from maintainer @humm - is this fine by you? I can take over maintainership if needed) took over maintainership, b4 from testing to community. This should also cause the packages to get bumped against the latest Python 3.12 version. Also fixes tests for git-filter-repo.