Log Message:
py-setuptools_scm: updated to 6.4.2

v6.4.2
======
* fix 671 : NoReturn is not avaliable in painfully dead python 3.6

v6.4.1
=======
* fix regression 669: restore get_version signature
* fix 668: harden the selftest for distribution extras

6.4.0
======
* compatibility adjustments for setuptools >58
* only put minimal setuptools version into toml extra to warn people with old \ 
strict pins
* coorectly handle hg-git self-use
* better mercurial detection
* modernize packaging setup
* python 3.10 support
* better handling of setuptools install command deprecation
* consider ``pyproject.tomls`` when running as command
* use list in git describe command to avoid shell expansions while supporting \ 
both windows and posix
* add ``--strip-dev`` flag to ``python -m setuptools_scm`` to print the next \ 
guessed version cleanly
* ensure no-guess-dev will fail on bad tags instead of generating invalid versions
* ensure we use utc everywhere to avoid confusion