Python: add py3.12 to unit tests (#5191)

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Since Python 3.12 is now released we should test with it. In the fall
3.8 will be out of support so then we should remove support for that.

Since Numpy no longer support py 3.8 as of
[1.25](https://numpy.org/doc/stable/release/1.25.0-notes.html) we pin
that for py3.8, including other packages that depend on older version of
numpy for py3.8, and allow the new versions to work against newer
version of python.

Closes #5144 

### Description

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- [x] All unit tests pass, and I have added new tests where possible
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