Add link to Github on PyPI page

Author: gahjelle

pyproject.toml

@@ -30,6 +30,10 @@ requires-python    = ">=3.6"
 requires           = []
 
 
+[tool.flit.metadata.urls]
+"Source Code" = "https://github.com/realpython/codetiming"
+
+
 [tool.flit.metadata.requires-extra]
 dev                = ["black", "bumpversion", "flake8", "flit", "mypy"]
 test               = ["pytest", "pytest-cov", "tox"]