beets: Add patch to fix Python 3.7 compatibility
beets: Add patch to fix Python 3.7 compatibility

Since 0f38d9669ffd74991b65a9c40cdbcf2a98438d1f, the default Python
version for Python 3 is now Python 3.7.

It has been a while since beets had a new release, but the fix for
Python 3.7 is already in master (and it's also rather small), so I
decided to cherry-pick the commit as a patch.

I've built the package along with its tests and they failed at first,
but the errors were unrelated. So I disabled the tests for pylint, as
they're failing right now.

In addition I also needed to temporarily revert
0d2f06ae3a1f8347dc09cd0dfe6d12b757368e4d, which supposedly should fix
issues with Python 2 but aparently breaks Python 3 support and during
the beets tests we get a ModuleNotFoundError for the "_gi_gst" module.

However I didn't further investigate why this happens, as I'm time
constrained right now. But after disabling the pylint tests and the
revert of the mentioned gst-python commit, the beets tests succeed.

Signed-off-by: aszlig <ee1aa092358634f9c53f01b5a783726c9e21b35a@nix.build>
Cc: e311c7e70bef45720cb4cf7488cccbc7fc58e6bd@lopsided98 (for introducing the gst-python change)
Cc: 60856e888312482b259865a0984b39ddd4058264@pjones (other beets maintainers)

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