REL: v3.8.1

This is the first bugfix release of the 3.8.x series.

This release contains several bug fixes and adjustments:

• Bump setuptools required version because of setuptools_scm v8
• Update find_nearest_contour and revert contour deprecations
• allsegs and allkinds return individual segments
• Restore default behavior of hexbin mincnt with C provided
• Try/except import of Axes3D
• Ensure valid path mangling for ContourLabeler
• BLD: Remove development dependencies from sdists
• FIX 2-tuple of colors in to_rgba_array
• Fix issue with non-string labels and legend
• Fix issue with locale comma when not using math text
• Various type hinting improvements
• Various documentation improvements
• Improvements to the MacOS backend