Add Python 3.12 and 3.13 to the testing

[cclauss]

No description provided.

[lbolla]

Tests fail for Python 3.13: missing setuptools?

Do you want to take a look and propose a fix for it?

[cclauss]

There were two problems:

1. setuptools was removed by default in Py3.12 and pytest needed it.
2. python setup.py xxx was also deprecated so just call pytest instead.

% pytest

============================= test session starts ==============================
platform linux -- Python 3.13.3, pytest-8.4.0, pluggy-1.6.0
rootdir: /home/runner/work/EMpy/EMpy
collected 8 items

tests/materials_test.py ......                                           [ 75%]
tests/utils_test.py ..                                                   [100%]

============================== 8 passed in 1.17s ===============================

[lbolla]

Great, thanks!