Simplify the typing annotations

libmat2/__init__.py

libmat2/abstract.py

libmat2/archive.py

libmat2/audio.py

libmat2/bubblewrap.py

libmat2/epub.py

libmat2/exiftool.py

libmat2/harmless.py

libmat2/images.py

libmat2/office.py

libmat2/parser_factory.py

libmat2/pdf.py

libmat2/torrent.py

libmat2/video.py

libmat2/web.py