[kayleeCromwell]

Description

Fixes #5348.
proposed solution: The playlist plugin accepts library for relative_to however smartplaylist treated every value as a path. Setting relative_to: library made paths relative to a folder named library in the current directory, rather than to the music library. This makes smartplaylist accept library for both the relative_to option and the relative-to flag. Paths are then made relative to the library directory, so the two plugins can be used together without a hardcoded path.

To Do

• [ x] Documentation. (If you've added a new command-line flag, for example, find the appropriate page under docs/ to describe it.)
• [x ] Changelog. (Add an entry to docs/changelog.rst to the bottom of one of the lists near the top of the document.)
• [ x] Tests. (Very much encouraged but not strictly required.)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.85%. Comparing base (e170aee) to head (876e2d6).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7175      +/-   ##
==========================================
+ Coverage   80.82%   80.85%   +0.02%     
==========================================
  Files         150      150              
  Lines       21209    21212       +3     
  Branches     3239     3240       +1     
==========================================
+ Hits        17143    17150       +7     
  Misses       3248     3248              
+ Partials      818      814       -4     

Files with missing lines	Coverage Δ
beetsplug/smartplaylist.py	91.34% <100.00%> (+2.74%)	⬆️

... and 4 files with indirect coverage changes

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.