Use trusted publisher

[jarrodmillman]

Description

The 0.22.0rc0 wheels and source tarball didn't get uploaded to PyPI because

WARNING  Error during upload. Retry with the --verbose option for more details. 
ERROR    HTTPError: 401 Unauthorized from https://upload.pypi.org/legacy/       
         User *** has two factor auth enabled, an API Token or Trusted      
         Publisher must be used to upload in place of password.                 
Error: Process completed with exit code 1.

I enabled GH as a trusted publisher for PyPI:

I tested this approach with devstats:
scientific-python/devstats#39

It seemed to work except that I ran into this issue:

$ twine check dist/*
Checking dist/devstats-0.1rc4-py3-none-any.whl: PASSED
Checking dist/devstats-0.1rc4.tar.gz: PASSED with warnings
WARNING  `long_description` missing.     

But I believe long_description from setup.py was replaced with readme in pyproject.toml:
https://packaging.python.org/en/latest/specifications/declaring-project-metadata/#readme

It doesn't cause an error and everything got uploaded to PyPI, but I thought that the readme from pyproject.toml would populate the Project description here:
https://pypi.org/project/devstats/

I will test this out with 0.22.0rc1.