Move to trusted publisher release management

[inakleinbottle]

PyPI and GitHub support trusted publisher releases, rather than fixed-token releases. It's quite clear that the trusted publisher is the way that PyPI will officially support releases in the future, and we should update our deploy action to reflect this.

I already set up (probably incorrectly) the permissions on the PyPI side, but I did not manage to make it work with the GitHub action.