Drop Python 3.9

[trin94]

Hi again!

Python 3.9 is end of life now, so I think it is a good time to drop it. Python 3.9 is not compatible with all latest versions of our dev-dependencies.

I made three small commits so it is easy to read: drop 3.9, remove some dead config, and add the missing tox env for 3.14.

One thing to check: CHANGES and the README assume 5.5.0 but it is your call if you prefer 6.0.0.

I also have a question: Would you be okay with using uv and adding a uv.lock file? You seemed open to it in #119. The main benefit is that we can pin the dev tools. Right now ruff is not pinned, and we run it with all rules plus preview. So every new ruff release can add errors and break CI for no real reason. With a lock file we could update ruff when we want.

If you like the idea, I can prepare a draft so you can see how it looks. I would also be happy to clean up the code a bit over time, and maybe try a newer type checker like pyrefly or ty later.

No problem if you do not want to.

Best
Elias

[ivankorobkov]

Hi!

Python 3.9 is end of life now, so I think it is a good time to drop it.

Sure.

CHANGES and the README assume 5.5.0 but it is your call if you prefer 6.0.0.

5.5.0 is better.

Would you be okay with using uv and adding a uv.lock file?

Yes.

If you like the idea, I can prepare a draft so you can see how it looks.

Yes, of course.

I would also be happy to clean up the code a bit over time, and maybe try a newer type checker like pyrefly or ty later.

OK.