Non-Github URLs in PyPI packages result in 0 score

[reuse](https://github.com/fsfe/reuse-tool/) has this in `setup.py`:

setup(
name="reuse",
url="https://reuse.software/",
project_urls={
"Documentation": "https://reuse.readthedocs.io/",
"Source": "https://github.com/fsfe/reuse-tool",
},
[...]
)

It is afforded a 0 score in the "Source" section by the crawler. I have cursorily checked some other PyPI packages, and it appears to me that all packages that do not point to GitHub in the `url` section also get a 0 score. This seems like a bug to me.