chore: move to scikit-build-core

[henryiii]

Summary

Include a summary of major changes in bullet points:

• Use scikit-build-core
• Set version in pyproject.toml

Additional dependencies introduced (if any)

• Scikit-build-core
  (removing some too, including setuptools)

TODO (if any)

• Test pip install

Checklist

Work-in-progress pull requests are encouraged, but please put [WIP]
in the pull request title.

Before a pull request can be merged, the following items must be checked:

• Code is in the standard Python style.
  Run Black on your local machine.
• Docstrings have been added in the Sphinx docstring format.
• Type annotations are highly encouraged.
• Tests have been added for any new functionality or bug fixes.
• All existing tests pass.
• The version number in flare/_version.py is updated. We are using a version number format a.b.c
  • If this PR fixes bugs, update version number to a.b.c+1
  • If this PR adds new features, update version number to a.b+1.0
  • If this PR includes significant changes in framework or interface, update version number to a+1.0.0

Note that the CI system will run all the above checks. But it will be much more
efficient if you already fix most errors prior to submitting the PR.

[jonpvandermause]

@anjohan, is this something we want to pursue? I'm inclined to close given the age of these commits and the failing builds

[henryiii]

Let me know if you want me to rebase.

[jonpvandermause]

Thanks @henryiii, that would be helpful. As long as we can get the build passing I don't see a reason not to use scikit-build-core; it looks like it would be a solid improvement over our current approach.

[anjohan]

@anjohan, is this something we want to pursue? I'm inclined to close given the age of these commits and the failing builds

Yes, ideally, as I think this would be a substantial improvement (and simplification). It's just been below the greater cleanup (deleting 2+3, old OTF etc.) on the priority list.

[jonpvandermause]

Yes, ideally, as I think this would be a substantial improvement (and simplification).

Yeah, I've looked into it a bit and agree, definitely an improvement. @henryiii I'm rebasing on a separate branch, so no need to spend time on this -- I will let you know if I hit any snags.

It's just been below the greater cleanup (deleting 2+3, old OTF etc.) on the priority list.

We should probably talk about the plan here, I would prefer to keep the old code in place in case other groups want to reproduce published results or try similar experiments

[jonpvandermause]

Looks like github is showing the entire history of the repo since @henryiii's fork was created, making the merge pretty hard to read. I've made an identical but cleaner version of this PR over at #416, so I'm going to close this one out.