Add framework matplotlib to classifiers

[jlaehne]

As suggested at https://github.com/matplotlib/mpl-third-party?tab=readme-ov-file

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.75%. Comparing base (12e986f) to head (c4d6893).

Additional details and impacted files

@@                  Coverage Diff                   @@
##           RELEASE_next_minor    #3336      +/-   ##
======================================================
+ Coverage               80.55%   80.75%   +0.20%     
======================================================
  Files                     147      147              
  Lines                   21871    21871              
  Branches                 5144     5144              
======================================================
+ Hits                    17618    17663      +45     
+ Misses                   3036     2990      -46     
- Partials                 1217     1218       +1     

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