Upgrading python versions (and adding nox)

[dylanjmcconnell]

Closes #30 - drop support / testing of python 3.9, and 3.10 (3.9 EoL, 3.10 EoL this year, and PyPSA 1.0 requires >3.11) and add in 3.13, 3.14. Some third party libraries didn't install with 3.14t (so not supported for now).

• Added a noxfile.py (for local testing of python versions, before CICD).
• Updated pyproject.toml
• Updated cicd.yml*

*Discovered a significant bug in cicd.yml (we weren't actually testing different python versions, just 3.12). Hopefully also fixed / corrected (and turns out we weren't actually supporting 3.9 anyway - (some of our typing syntax requires >3.10)

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[dylanjmcconnell]

.. Additionally updated uv.lock file for python version compatibility (I think a --frozen issue)

[nick-gorman]

Hi Dylan, a few thoughts below:

• Should we just not test 3.14 as its unstable and could break, also a bit confusing if we are testing for it but not supporting it?? not sure.
• Should nox be a dev dependency? and should we breifly document how to run the noxfile?
• is this technically a breaking change requiring a major version bump

[nick-gorman]

see previous comment

[dylanjmcconnell]

Thanks Nick! Some responses, in order:

• 3.14 is certainly stable release (released Oct last year). 3.14t (i.e. free-threaded python) is the one I dropped / didn't test (or include in CICD). It is also technically stable, but a handful of libraries currently don't have wheels or don't build. I think we should leave 3.14, but not include 3.14t yet (i.e. essentially as it currently is).
• No, I don't think nox is a dev dependency (..more of tool, like say git, pip or uv). Not typically installed at project level / not typically a project dependency ( orchestrates environments, it doesn't run inside them - potentially creates some circularity too? As in, nox creates isolated envs, but would need to be installed first to install itself? Not sure - but sort of the same as why you don't have uv,pip,git as a dev dependency) . Will add a note to the contributing.md guidelines (and suggest local version testing is optional - we have not really done this to date mind you).
• Good point on breaking change. Generally, I think adding new python versions is not breaking, but removing old ones is. In this case, we weren't actually really supporting 3.9 - so that is already broken in a sense (and making 3.,9 work would require code changes, which we shouldn't do). In this case, suggest dropping (only) 3.9, keeping 3.10 for now (and dropping for a bigger / later breaking change).

[nick-gorman]

Hey Dylan, yep, thanks for clarifying, I'd misunderstood a few things, and it sounds good re-adding 3.10 back in.