PyPI now supports digital attestations

Here is the GitHub issue you can subscribe to for automatically generated attestations in the GitHub CI PyPi upload action: https://github.com/pypa/gh-action-pypi-publish/issues/288

Just a note: that issue is for connecting the already-present attestations to GitHub's attestations feature[1]. Attestations are already automatically generated and uploaded to PyPI regardless of that issue.

(That issue will still be great to resolve, but just to avoid any confusion about its scope.)

[1]: https://docs.github.com/en/actions/security-for-github-actio...