VBA - axis labels via geopandas add_labels (supersedes #306)

[sjsrey]

This PR

• resolves retain unlabeled axis behavior in vba_choropleth() #305
• supersedes VBA - retain unlabeled axis plotting behavior #306 — builds on @jGaboardi's commit there (rebased onto main) and revises it to use the add_labels keyword from ENH: allow control of axis labels addition via add_labels in plot geopandas/geopandas#3767, released in geopandas 1.2.0, as discussed in VBA - retain unlabeled axis plotting behavior #306

Changes on top of #306:

• vba_choropleth passes add_labels=axis_labels to GeoDataFrame.plot() when geopandas>=1.2.0; older versions never add axis labels, so nothing is passed there. The manual set_xlabel("")/set_ylabel("") is dropped.
• version check uses importlib.metadata (no runtime dependency on packaging)
• label test gated on geopandas>=1.2.0 (the previous >1.1.3 gate would include 1.1.4, which lacks add_labels)
• axis_labels docstring corrected (True adds labels)
• crs_labels.png baseline regenerated at the post-TST: matplotlib 3.11 compatibility #313 (matplotlib 3.11) size; tests now also assert labels are present with axis_labels=True and absent by default

Tested locally: full suite passes with geopandas 1.2.0 / matplotlib 3.11.2; with geopandas 1.1.3 the label test is skipped and the rest pass.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.2%. Comparing base (42f740a) to head (576901c).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #323   +/-   ##
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  Coverage   90.1%   90.2%           
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  Files         11      11           
  Lines       1309    1314    +5     
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+ Hits        1180    1185    +5     
  Misses       129     129           

Files with missing lines	Coverage Δ
mapclassify/value_by_alpha.py	91.3% <100.0%> (+0.4%)	⬆️

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[martinfleis]

Why don't we just pass kwargs in general? If we don't have a strong reason to remove the labels, we could even inherit geopandas behaviour and its controls here.

[jGaboardi]

@martinfleis Would you be able to provide an example of that? (how it differs from @sjsrey's code)

[martinfleis]

 vba_choropleth(
    x,
    y,
    gdf,
    [...],
    **kwargs,
):
    [...]
    gdf.plot(color=rgba, ax=ax, **kwargs)
    [...]

just like this. This could be the whole diff of the PR. This automatically allows stuff like tiles=True, new automatic handling of labels in subplots and related change of the add_labels default to None etc. I don't think we need to do anything special here and I am not sure why we would want to deviate from geopandas and set add_labels to False by default.