Update license to pep639 standard

[wagenrace]

Summary

In pep 639 the classifier for licenses gets deprecated in favor of the license field.
The benefits for UV:

• Clear that you can pick a license, not have to have both
• Clear it is version 2 for the Apache license

https://peps.python.org/pep-0639/

Test Plan

Builds, works.
If the license shows up in pypi.org with the SPDX operator, it works

[zanieb]

We've tried updating this before and it broke our release process.

[wagenrace]

I see the red in the workflows
Is it the pipelines or the older versions of Python?

Might want to look at it but do not want to reinvent to much

[wagenrace]

The error I see is "Error: failed with: Error: missing API token, please run depot login"
I do not think this is code-related, right?

[zanieb]

The Depot / Docker thing is unrelated.

[zanieb]

I can't seem to find the failure from the previous attempt. @konstin may remember.

[konstin]

It's in astral-sh/ruff#19499 and the revert PRs. It should be fixed in maturin now but we should double check so we don't fail at the PyPI upload stage.

[wagenrace]

Can that be tested without merging?
Uploading to test.pypi.com?