python 3.11 beta introduces zipfile changes that break apksigcopier

Should be fixed on apksigcopier's upstream master (and hopefully I will be able to release a new version soon), but the vendored copy in fdroidserver needs to be updated (though since python 3.11 is still in beta -- with a final release, which could contain further changes I suppose, scheduled for 2022-10-03 -- it should not be urgent).

Edit: I've reported this as a bug in python: https://github.com/python/cpython/issues/95463