Avoid using deprecated import from glue-core

[astrofrog]

This removes the last deprecated import from glue-core and also makes pytest_unconfigure more robust to issues in test setup

[codecov]

Codecov Report

Attention: Patch coverage is 33.33333% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 69.04%. Comparing base (44eae90) to head (9c7b714).
Report is 1 commits behind head on main.

Files	Patch %	Lines
glue_wwt/conftest.py	33.33%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #105      +/-   ##
==========================================
- Coverage   69.11%   69.04%   -0.07%     
==========================================
  Files          18       18              
  Lines        1023     1024       +1     
==========================================
  Hits          707      707              
- Misses        316      317       +1     

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