Fix jeff CI issue

[mokagio]

Fixes #20

• Fix extract() crash: shutil.rmtree() was called with a list instead of a single path, and isinstance misclassified strings as iterables
• Make openmc import optional so the package can be imported in CI environments without native OpenMC
• Trigger CI jobs on utils.py changes and fix stale workflow paths

[shimwell]

Thanks for the PR

CI has an error but i think it is unrelated to this PR

[4](https://github.com/openmc-data-storage/openmc_data/actions/runs/24239400688/job/70781851809?pr=26#step:6:855)
         ^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.12.13/x64/lib/python3.12/site-packages/openmc/data/endf.py", line 82, in __init__
    if fh.tell() == 0:
       ^^^^^^^

Which I have a fix for over here paulromano/endf-python#40

Let us see if that can be merged and come back to this soon