Please also build an sdist for PyPI

[smith120bh]

First off - I love that you've done this. Thank you so much! I was looking to do something similar myself in rebuilding triangle to work correctly on multiple architectures, but just did not have time to get to it, and you've done a more careful job than I would have.

I would like to request that you also upload an sdist source distribution to PyPI. While the wheels you're building cover almost all cases that someone might want, they don't quite cover everything. We have a case where we're running a docker container of a linux distribution on MacOS arm64 machines - so technically need a manylinux/arm64 wheel. It's probably a waste for you to build those wheels in your GitHub Action here, but if you include a source distribution then anyone can build whatever weird combinations of Python/OS/arch that might work.

I'm also happy to PR a patch to do this :-)