Update pypa/gh-action-pypi-publish to v1.12.4

[mitya57]

This is the first tag with support for metadata format 2.4 (including PEP 639), see pypa/gh-action-pypi-publish@10df67d.

This should fix the deploy action, which currently fails with the following error:

Make sure the distribution includes the files where those fields are specified, and is using a supported Metadata-Version: 1.0, 1.1, 1.2, 2.0, 2.1, 2.2, 2.3.

Although I have no good way to test that.

[waylan]

Although I have no good way to test that.

The next release we do should probably be a prerelease (one of alpha/beta/rc). That way if deployment fails, we can just increment (beta1, beta2...) and re-release. In the meantime, it looks like I will need to manually deploy the 3.8 release.