enhancements
- Following [PEP-517](https://peps.python.org/pep-0517) and [PEP-518](https://peps.python.org/pep-0518) standards, the direct use of `setup.py` is discouraged and `pyproject.toml` should be used instead. In this release the most of `setup.py` settings are ported to `pyproject.toml`
- In addition:
- Versioning is centralised at single place, in `pyproject.toml` file
- Unit tests are added to validate the build and check the wheel and source distribution content. Build process may be changed in the future, like removing `MANIFEST.in`, following [PEP-518](https://peps.python.org/pep-0518) finalisation