CI FIX: Make sure setuptools_scm is installed for sdist building

There was a little snafu with the pypi upload for the new tag after switching to setuptool_scm. Due to a known issue with setuptools the code was tagged as v0.0.0.

The fix is to make sure setuptools_scm is installed in that job. I've run a test that the dist will build properly. I'll revert some of the CI changes when that passes.

(I manually pushed the tag with the correct label to pypi.)