python-mutagen: remove

[cho-m]

==> Analytics
install: 2,429 (30 days), 10,893 (90 days), 35,910 (365 days)
install-on-request: 60 (30 days), 178 (90 days), 519 (365 days)
build-error: 0 (30 days)

Need to check on previous dependents:

• bandcamp-dl - adb-enhanced bandcamp-dl mackup spoof-mac west: revision bump for python-docopt removal #164152
• mat2 - mat2: revision bump for python-mutagen removal #164370
• yt-dlp

[p-linnane]

I took care of yt-dlp last week: #163262

[cho-m]

I took care of yt-dlp last week: #163262

More of situation on revision bumps. I may need to locally test out removals some more (particularly for users who don't run brew upgrade).

[cho-m]

I do think brew should block uninstallations of python-* packages if existing formula tab uses it. So probably okay without revision bumps. Can resolve if users complain later on. Most of time, issues seem like users see the "formula ... is removed" message and think something is broken when they can't uninstall it.