Add link to public git repository

[szabgab]

Add the link to point to the repository of the project so people looking at pypi can easily find it and contribute to this project. For explanation see https://packaging.python.org/en/latest/guides/writing-pyproject-toml/

[Giordano10]

Thank you for your recommendation. I will include this in my pyproject.toml. This will make my project much more visible.