Matplotlib 3.8
One of the windows runners accidentally started using Matplotlib 3.8rc1 yesterday for 3.0a18 Conda-Forge builds and it ended up failing. For now I'll limit the version to be installed but we should check this properly.
Matplotlib 3.8 also doesn't support python 3.8 anymore either, so we'll need more involved version checking.
Beginning with Matplotlib 3.8, Python 3.9 or above is required.
You are using Python 3.8.17.