REL: v3.8.1

This is the first bugfix release of th3 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
- Improvementes to the MacOS backend