Parse and scan dependencies from setup.py

[schuylermartin45]

Similar to #143 . I think setup.py is the second most common way Python projects declare dependencies after project.toml. Or it could be more, depending on how many projects use this older mechanism.

[schuylermartin45]

It appears setup.py is deprecated, but from personal experience, there might be enough projects still using it that we should pursue this path.

But before we do, we should check my assumption with data and see if adding this support is a viable use of our time.

[schuylermartin45]

Talking with our package building users, some anticipate that 50%+ of the projects they encounter still rely on setup.py. That means this is still worth pursuing.