update APK file regex
I've proposed a patch for file(1) to recognise APK files specifically, not just as ZIP (or sometimes JAR) files.
This patch has not (yet) been accepted by upstream; Christoph Biedl might include it in the Debian package.
This MR updates the libmagic file type regex, though diffoscope still works correctly without it even with the file(1) patch since it recognises the PK\x03\x04 file header instead.
I'm a bit confused by the fact that Dalvik dex file is also part of the regex currently, since .dex files are definitely not APK/ZIP files.
Maybe that should be removed? I can update the MR if so.
And lastly just a friendly reminder that I opened 2 more MRs 2 weeks ago which have not gotten any response yet; I just want to make sure they didn't accidentally get overlooked because of the holidays, I completely understand if people were simply been too busy to respond yet.