* wheel versions now replace `+` with `.post` to match spec at https://packaging.python.org/en/latest/specifications/version-specifiers/
* CI updates:
* Bump action versions
* Disabled Windows for now and documented why
* Added a new job to upload all wheels
* Added new variable, `PYPI_INDEX`: fallback 'https://pypi.org/' if unset
* Added new secret, `PYPI_TOKEN`
* .editorconfig now uses 2 spaces for YML (it kept setting mine to tabs
and GitHub Actions doesn't like that)