Create PyPI release workflow

For historical reasons, releases are made locally. Add the github-release workflow for pypi. Check `BUILD.rst` for current approach for releases.
Goals are:
- easier release process
- unified release process
- limit rights on pypi organization

- [ ] SSHLibrary pre-releases are published automatically when creating a Github release
- [ ] SSHLibrary release are published automaticall when creating a Github release
- [ ] SSHLibrary release can be published on test-pypi
- [ ] Pypi Token is added to Github secrets with most restrictive permissions

Start by reading BUILD.rst for the current local release approach, then inspect the repository's existing GitHub workflow configuration. The work is complete when GitHub releases publish both pre-releases and releases to PyPI, releases can target TestPyPI, and the PyPI token is stored in GitHub secrets with the most restrictive permissions.

Written by the indexing model from the issue text.