FIX/MAINT: np.infty -> np.inf (numpy 2.0 compat)

[richardotis]

One more Numpy 2.0 compatibility issue (missed because the plotting code wasn't run in the test suite). This PR adds a 'functional' test (i.e. does it run without errors) for binplot to ensure we don't miss potential deprecations or other regressions in the plotting module.

[codecov]

Codecov Report

Attention: Patch coverage is 85.71429% with 2 lines in your changes missing coverage. Please review.

Project coverage is 90.86%. Comparing base (da2bbbb) to head (a87171c).
Report is 1 commits behind head on develop.

Files	Patch %	Lines
pycalphad/plot/binary/compsets.py	33.33%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #538      +/-   ##
===========================================
+ Coverage    90.31%   90.86%   +0.55%     
===========================================
  Files           50       50              
  Lines         7885     7892       +7     
===========================================
+ Hits          7121     7171      +50     
+ Misses         764      721      -43     

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