Fix missing toml extra w/ setuptools-scm (GH-2475)

Project packaging is using TOML due to pyproject.toml but fails to
mention it, causing installation failures with newer setuptools-scm 6.3.0.

Commit history before merge:

* Fix missing toml extra

Fixed breakage uncovered by setuptools-scm 6.3.0 where installation
would fail for project that missed to mention the toml extra.

* Bump setuptools[-scm] to avoid toml extra

https://github.com/psf/black/pull/2475#issuecomment-912730714



> If you constraint greater than 6.3.0 and setuptools greater than 45
> you can skip the extra,

* Actually for safety reasons, just use the extra

Co-authored-by: Richard Si <63936253+ichard26@users.noreply.github.com>