Python 3.7/3.8 EOL update

[goulart-paul]

Produce python abi3 outputs with MSV python 3.9. This remains compatible with cvxpy, which also requires >= 3.9.

Updating now since some CI builds have begun failing on ubuntu-latest with python 3.7.

Internal updates for compatibility with pyo3 v0.23 to support python 3.13.

Fixes #146

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 88.12%. Comparing base (7036899) to head (fd87e73).
Report is 2 commits behind head on develop.

Files with missing lines	Patch %	Lines
src/python/pyblas/mod.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #147      +/-   ##
===========================================
- Coverage    88.14%   88.12%   -0.02%     
===========================================
  Files           77       77              
  Lines         6189     6189              
===========================================
- Hits          5455     5454       -1     
- Misses         734      735       +1     

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