rf(py314): Replace deprecated pkgutil.find_loader

[effigies]

This PR removes pkgutil.find_loader() and replaces it with importlib.util.find_spec(). find_loader was deprecated in Python 3.12 and will be removed in 3.14. find_spec has been present since Python 3.4.

Both functions return None if the module loader cannot be found. For its use in this project, this is sufficient and no translation of the return value is needed.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 30.59%. Comparing base (063b33e) to head (72f9c67).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/fmripost_aroma/cli/parser.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #81   +/-   ##
=======================================
  Coverage   30.59%   30.59%           
=======================================
  Files          26       26           
  Lines        2363     2363           
  Branches      286      286           
=======================================
  Hits          723      723           
  Misses       1617     1617           
  Partials       23       23           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.