Confusing handling of 'magic' dependency

[ferdnyc]

(referencing the Fedora python3-eyed3 distro package)...

...Oh, awesome, even better. It doesn't have a dependency on any magic package!

...Then again, neither does eyeD3 itself, that I can find. Despite being used in plugins/mimetypes.py, python-magic never appears in pyproject.toml or any of the requirements/ files.

Originally posted by @ferdnyc in #637 (comment)

The HISTORY.rst file contains a confusing saga of various changes revolving around mimetype detection... python-magic seems to have been added and removed as a dependency at least three times over the years.

Currently, however, it does not appear as a dependency anywhere in the eyeD3 package metadata.

But plugins/mimetype.py still has code that attempts to import magic and set up a MagicTypes class subclassed from magic.Magic.

Which can be a problem, because doing an import magic in a random distro Python install may import file-magic, the Python libfile bindings (https://github.com/file/file/), instead of python-magic. Both packages have a magic.Magic class, but their APIs are completely different and incompatible.

I think eyeD3 probably needs to continue specifying which magic it's dependent on. (Specifically, python-magic.)