Update to modern packaging
See individual commits.
I think this likely fixes #140 after a new release.
Oops, sorry about the CI failures, I had neglected to update the Github Actions config. Could you give it another go?
Alright, this should be green for real now. I worked out the kinks by running CI in my fork.
@mystor does this look reasonable to you?
@mystor gentle ping.
Please let me know if changes are required - or go ahead and make what changes you see fit. I've allowed edits by maintainers and you have my explicit consent to edit directly.
Thanks! This seems like a solid direction for modernizing the tooling we're using.