REL: v3.7.3

This is the third bugfix release of the 3.7.x series.

This release contains several bug-fixes and adjustments:

* Add Python 3.12 wheels
* Update the license for the bundled colorbrewer colormap data
* Fix Cairo backend when using cairocffi
* Fix axes_grid1 inset axes with `bbox_inches=tight`
* Fix bugs in `Path3DCollection` / `Poly3DCollection` constructors
* Fix setting array labelcolor on Tick
* Improve compatibility with latest NumPy
* Stop warning when calling `tight_layout` multiple times