Move from "test.pypi.org" to the real pypi.org

[ctrl-z-9000-times]

Currently we're releasing python packages to pypi's test server, not their production server.
It would be nice if this project were located on the production server.

If it were on the production server, then installation would be as simply as pip install htm-core

See file .github/workflows/release.yaml
Line 208-214:

    - name: Publish to PyPI
      uses: pypa/gh-action-pypi-publish@master
      with:
        user: __token__
        password: ${{ secrets.pypi_password }}
        repository_url: https://test.pypi.org/legacy/ #TODO toggle test/real pypi
        packages_dir: ./dist/

[ctrl-z-9000-times]

Before the next release: don't forget to also modify the README file to indicate what combinations of Python and platform that are supported in pypi.