Support Python 3.13

[john-science]

Python 3.13 is expected to be released on 2024-10-01.

I have a branch ready to test this: py_313.

I have already tested ARMI against the dev versions of Python 3.13, but the problem right now is that SciPy does not yet support Python 3.13. So that is our current stopping block (thought it may be there are other libraries that also don't fully support 3.13 yet).

[john-science]

As a fun aside, I had to make a few changes to test out dev versions of Python 3.13:

armi/.github/workflows/unittests.yaml

Lines 17 to 25 in 068484d

	python: [3.9, '3.10', '3.11', '3.12', '3.13']
	steps:
	- uses: actions/checkout@v4
	- name: Setup Python
	uses: actions/setup-python@v5
	with:
	python-version: ${{ matrix.python }}
	allow-prereleases: true

As stated here, I found I could add "3.13" to the Python version list as long as I added allow-prereleases: true as well. But that feature wasn't supported unless I used a more modern version of the Python installation action: actions/setup-python@v5.

This also makes me notice that we are using an older version of the Git action as well, and that could be updated: actions/checkout@v4.

[john-science]

Update:

• SciPy supported Python 3.13!
• Now the road block is ruamel.yaml does not support Python 3.13; it won't even install.