feat(ci): switch to uv publish for PyPI uploads

[woodruffw]

This switches pypi-publish.yml from gh-action-pypi-publish to uv publish. The upload itself is still through Trusted Publishing, and attestations are preserved through astral-sh/attest-action (which can be removed in the medium-term, once uv publish itself supports attestation generation).

Noting a few things from conversation with @reaperhulk:

• This runs uv publish directly, since the uv binary is configured on the $PATH implicitly via astral-sh/attest-action. This is arguably undesirable, since cryptography otherwise pins uv via a requirements file.
• Separately, this currently runs the latest uv release at all times, since astral-sh/attest-action doesn't attempt to pin it (besides a lower bound for compatibility). This is "ok" from Astral's own trust domain, but it might not be what you want in your release pathway for stability/reproducibility purposes.

TL;DR: This all works, but the current approach may not be what you want in terms of version pinning.

[woodruffw]

(My plan here is to make attest-action hard-pin the uv version, and then release a new version that I'll bump to in this PR.)

[alex]

Is uv in the base image? If not, it's not installed here.

[woodruffw]

It's installed implicitly via attest-action, since workspace tools are global state. I find this kind of spooky/scary though.

[alex]

please add a comment at least

[alex]

Oh I just realized this won't work, since attest-action only runs conditionally on it being a push to prod pypi.

[alex]

I think this is still an issue.

[woodruffw]

Yep, was going to fix it today. Sorry for the re-ping from the new activity.

[woodruffw]

Okay, I've added a setup-uv to ensure uv is always present. This feels kind of wrong given that you use python -m pip install -c ci-constraints-requirements.txt 'uv' elsewhere, but the alternative would be to increase the size of the publish job here significantly (with a checkout + setup-python).

[alex]

Does this also hash pin the version of uv that's installed?

[woodruffw]

Yes, although it's a floating resolution (the action knows all of the hashes, and selects the latest version). That doesn't seem ideal though, and it's an additional failure point with GitHub's unreliability. I'm going to switch it to the same constraint approach you use elsewhere 🙂

[alex]

Yeah, we want everything pinned to a particular version. Only way to avoid shit breaking when we need it to work.