fix(python): Change recognition of numba ufunc

[deanm0000]

At some point/version of numba or numpy "they" made it so the ufunc that gets handed to __array_ufunc__ changes its class so that looking at the class doesn't distinguish a numba ufunc from a native numpy ufuncs. This is relevant because all the numpy/scipy native ufuncs are elementwise whereas the numba ufuncs probably aren't.

Luckily, it still is the case that ufuncs produced by numba have a signature field whereas the native ufuncs have signature None so I just switched the custom ufunc to that check.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.23%. Comparing base (a9c8b59) to head (90e9d19).
Report is 4 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main   #15916       +/-   ##
===========================================
+ Coverage   39.14%   81.23%   +42.09%     
===========================================
  Files        1364     1382       +18     
  Lines      167705   176628     +8923     
  Branches     3031     3032        +1     
===========================================
+ Hits        65646   143488    +77842     
+ Misses     101592    32655    -68937     
- Partials      467      485       +18     

Flag	Coverage Δ
python	74.67% <100.00%> (+35.53%)	⬆️
rust	78.36% <0.00%> (+39.21%)	⬆️

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