Add GitHub Actions workflow for PyPI publishing

[virtualzx-nad]

This PR adds GitHub Actions workflow for automated PyPI publishing as discussed in #4.

Changes:

1. Added GitHub Actions workflow that:
   • Tests package installation and basic functionality on Python 2.7-3.9
   • Publishes to PyPI when a new release is created
2. Added pyproject.toml for modern Python packaging
3. Added MANIFEST.in to include README.md and LICENSE

I've verified locally that:

• Package builds correctly with python -m build
• Wheel contains all necessary files
• Package installs and imports correctly

To publish to PyPI after merging:

1. Create a PyPI account
2. Generate an API token
3. Add the token as a GitHub repository secret named PYPI_API_TOKEN
4. Create a new release

Closes #4

[patrickmelix]

Also works for me locally, thanks for doing this!