fix: don't update locked fields + unlock fields after update

[zdimension]

Description

Locked fields will not be updated by Themerr. Fields updated by Themerr will be marked as non-locked.

Screenshot

Issues Fixed or Closed

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Dependency update (updates to dependencies)
• Documentation update (changes to documentation)
• Repository update (changes to repository files, e.g. .github/...)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated the in code docstring/documentation-blocks for new or existing methods/components

Branch Updates

LizardByte requires that branches be up-to-date before merging. This means that after any PR is merged, this branch
must be updated before it can be merged. You must also
Allow edits from maintainers.

• I want maintainers to keep my branch updated

[codecov]

Codecov Report

Merging #208 (a89b952) into nightly (12c78b8) will decrease coverage by 1.29%.
The diff coverage is 16.27%.

Additional details and impacted files

@@             Coverage Diff             @@
##           nightly     #208      +/-   ##
===========================================
- Coverage    67.75%   66.47%   -1.29%     
===========================================
  Files           11       11              
  Lines          856      874      +18     
===========================================
+ Hits           580      581       +1     
- Misses         276      293      +17     

Flag	Coverage Δ
Linux	66.47% <16.27%> (-1.29%)	⬇️
Windows	66.47% <16.27%> (-1.29%)	⬇️
macOS	66.47% <16.27%> (-1.29%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
Contents/Code/constants.py	85.71% <ø> (ø)
Contents/Code/plex_api_helper.py	45.94% <16.27%> (-2.62%)	⬇️

[ReenigneArcher]

I think these are the final adjustments. Also need to add a test for is_field_locked, I can take care of that if you'd like.

[ReenigneArcher]

The function is now a method for plex item objects in plexapi.

[ReenigneArcher]

Getting several timeout errors with the new api version. Also, it is often saying "Not overwriting locked theme for movie: ...".

https://github.com/LizardByte/Themerr-plex/actions/runs/6882298903/job/18721980967?pr=208#step:9:1169

[zdimension]

Good idea to use a retry loop; tested it on my local setup by introducing fake timeouts (just maxed out my IO usage so Plex would be slowed down, and the loop properly retried and failed gracefully at the first attempt instead of crashing the plugin