nightly-9682f24c-ls103

CI Report:

https://ci-tests.linuxserver.io/linuxserver/beets/nightly-9682f24c-ls103/index.html

LinuxServer Changes:

Pin beetcamp to 0.19.2 until upstream requirements fixed.

Remote Changes:

Lastgenre: New config option keep_existing (#4982)

New config option keep_existing (#4982)

• Fix the behavior of theforce option. Previously disabling the option
  had "incomplete" behaviour:
• If content was found, a whitelist check was issued and if valid the
  plugin exited early and logged ("keep").
• This whitelist check was not aware of multiple genres (separated
  typically by a string like , ), thus it failed erased all existing
  genres and overwrote with new ones.

This didn't feel like a typical behaviour of a force option, which
this PR tries to improve as follows...

• String-separated multi-genres are now compiled into a list and
  depending on the whitelist option are kept and enriched with freshly
  fetched last.fm genres.

• If force is off, pre-populated tags are not touched.

• A lot of refactoring was done, some absolutely required, some as a
  preparation for future work on the plugin.

• The main processing function _get_genre was massively overhauled and
  got a new pytest.mark.parametrize test which includes much more test
  cases.