Support Python >= 3.13

[foobacca]

This is currently blocked due to using mip==1.15.0 - which in turn depends on cffi 1.15. And that version of cffi does not work with python 3.13. It has been fixed, but as mip 1.15.0 hard codes cffi 1.15 we are stuck.

This has been fixed in mip 1.16.0rc0, but I'd rather wait for the proper 1.16.0 before upgrading.

References:

• python-mip issue about cbclib not defined : Name 'cbclib' is not defined coin-or/python-mip#335
• trying to use python-mip with python 3.13: The PyPi module cannot be installed with Python version 3.13 coin-or/python-mip#407
• python-mip - most used discussion about getting new version out with updated python and dependencies: Python 3.12 coin-or/python-mip#376

[foobacca]

Alternatively, if drop python-mip that would allow the upgrade.

See #67 and #30.

We can now use highspy - #67 has been merged. So we could decide to drop python-mip, though right now that would mean it would be slower.

[foobacca]

The cryptography package now has a vulnerability fixed in 46.0.5. It doesn't affect us (or OpenDLP) as it is a bit obscure, but it will show up in security scans.

But we can't upgrade to it with python-mip 1.15.0 present. (As it depends on cffi 1.15.x and cryptography 46.0.5 requires cffi>=2.)

I did try just installing python-mip 1.16rc0 but the tests fail - and there is no error message - see full output at end. The exit code is 134, which means the process received SIGABRT. So we can't use 1.16rc1. We might just have to drop mip and use highspy and live with the slower solver just to keep up-to-date dependencies.

---

Full output from test run:

❯ uv run pytest -vv -x
====== test session starts ======
platform linux -- Python 3.11.14, pytest-9.0.2, pluggy-1.6.0 -- /home/hamish/dev/sf/sortition-algorithms/main/.venv/bin/python3
cachedir: .pytest_cache
rootdir: /home/hamish/dev/sf/sortition-algorithms/main
configfile: pyproject.toml
testpaths: tests
plugins: cov-7.0.0
collected 369 items

tests/test_adapters.py::test_csv_selection_happy_path_defaults[legacy] PASSED
tests/test_adapters.py::test_csv_selection_happy_path_defaults[maximin] %
❯ echo $?
134