Do PyPI release in GHA

[danielballan]

Precisely following https://learn.scientific-python.org/development/guides/gha-pure/

This introduces GHA, alongside CircleCI. An additional integration is not ideal, bu there are points in favor:

• GHA, being a GH-internal integration, is not a big jump to make.
• We can use this community-supported recipe as is.
• GHA can handshake directly with PyPI via Trusted Publisher that we do not need to handle secrets in the environment. (It seems like it ought to be possible to do this with CircleCI, but some cursory Googling did not turn anything up.)

[Mr0grog]

That did not seem to make the workflow run here. It might just need to land in this repo (and not a fork) before it be run, or GH has to see some workflows in this repo before it understands that the workflow engine should kick in.

Anyway, I’m cool to ship this if you think it’s good, assuming I got the above stuff about intended usage correct.

[danielballan]

I think I've seen this before: GH will not run a new workflow on a PR branch.

Yes, that summary of the intended usage is precisely right.

I have just pushed a commit to remove the build section from the CircleCI config.