updated testing environment to python 3.12

[p5k369]

• added python 3.12 for testing
• updated github actions

[p5k369]

@eoyilmaz Damn. I should have marked it as not ready for merge. I build the wheels for wxpython-4.2.1 and python 3.12 and uploaded them.
But there is some problem with pytest. It has nothing to do with the tests. I think something goes wrong during import when calling pytest. Even if all tests are skipped calling python3 -m pytest will segfault, also locally. I assume it has something to do with RealDisplaySizeMM, but can't confirm that right now.

[p5k369]

I'm 95% sure it is because of some issue with the c-extension.

[p5k369]

I think I was wrong, seems like the segfault is bound to the import of wx into the test module.

[eoyilmaz]

Damn. I should have marked it as not ready for merge.

Aah, sorry about that.

I'm 95% sure it is because of some issue with the c-extension.

I started to think it is time to remove this c-extension. I'm going to go over it again, but as I understand it is only doing some mundane task there of finding what is the pixel equvelant of the given dimensions in mm, that is ultra unnecessary if you ask me.