Drop Python 3.9 support

[jameslamb]

Description

Contributes to rapidsai/build-planning#88.

Drops Python 3.9 support.

Notes for Reviewers

Is this safe for nvmath-python?

I think yes.

In an offline conversation, I was told that nvmath-python follows NEP 29 (https://numpy.org/neps/nep-0029-deprecation_policy.html) and so would want to drop Python 3.9 in its next release anyway.

That's documented in its docs as well:

https://github.com/NVIDIA/nvmath-python/blob/7c485842d0f3300e03ec780056936503913910fe/docs/sphinx/overview.rst?plain=1#L274

cc @leofang

How I tested this

Checked that there were no remaining uses like this:

git grep -E '3\.9'
git grep '39'
git grep 'py39'

And similar for variations on Python 3.8 (to catch things that were missed the last time this was done).

What are these other changes?

ruff raised two new errors here:

.ycm_extra_conf.py:24:5: N802 Function name `Settings` should be lowercase
pynvjitlink/patch.py:226:20: UP031 Use format specifiers instead of percent format
Found 2 errors.
No fixes available (1 hidden fix can be enabled with the `--unsafe-fixes` option).

Left Settings untouched... looks like ycm expects that to be exactly Settings (ycm-core docs).

The verify-copyright hook also complained about one file missing a copyright header

In file .ycm_extra_conf.py:1:1:
 import os
warning: no copyright notice found

So I added one.

[jakirkham]

Think Leo gets back next week. Let's wait for him to review

[jameslamb]

Ah right. Ok no problem! This doesn't block the rest of RAPIDS, it can happen at any time.

[leofang]

Thanks, James!

Addressed

[jameslamb]

/merge