remove unnecessary 'setuptools' dependencies

[jameslamb]

Contributes to rapidsai/build-planning#62.

It looks like this project's wheels and conda recipes have unnecessary dependencies on setuptools. I suspect those are left over from before the project was cut over to scikit-build-core.

This proposes removing those.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

Notes for Reviewers

How I confirmed there were no direct uses of setuptools in the project:

git grep -i setuptools

[jameslamb]

I believe the failing conda-notebook-tests job (build link) will be fixed once branch-24.06 is forward-merged into branch-24.08 (#1388).

[jameslamb]

/merge