automate schema version naming

[chrishavlin]

This ties the active schema version to the _version.py file so that it doesn't have to be manually updated.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (c90261c) 99.42% compared to head (27980da) 99.42%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #110   +/-   ##
=======================================
  Coverage   99.42%   99.42%           
=======================================
  Files          31       31           
  Lines        2427     2431    +4     
=======================================
+ Hits         2413     2417    +4     
  Misses         14       14           

Files	Coverage Δ
src/yt_napari/_schema_version.py	100.00% <100.00%> (ø)
...t_napari/_tests/test_schema_version_comparisons.py	100.00% <ø> (ø)
src/yt_napari/schemas/_version_comparison.py	100.00% <100.00%> (ø)

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