build: support python 3.14

[tlambert03]

closes #720

The key fix here is the fix to MagicParameter.__str__, to accomodate changes made to inspect.Parameter.__str__ in python 3.14. The rest is just to get tests passing again for random Qt issues

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.27%. Comparing base (cf45221) to head (acf0b79).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #721      +/-   ##
==========================================
+ Coverage   88.86%   89.27%   +0.40%     
==========================================
  Files          40       40              
  Lines        4815     4820       +5     
==========================================
+ Hits         4279     4303      +24     
+ Misses        536      517      -19     

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[tlambert03]

i had to sort of "cherry pick" OS/Qt/python versions here for some of the old qt versions (right here) in order to avoid segfaults. it's probably not super robust, but it's also outside of the scope of simply trying to support python 3.14. So I'm going with it.