Standalone installation missing some dependencies via pip

[anwai98]

Super minor, I just needed to install these via pip, and all the tests passed locally on the Windows machine like a charm ;)

1. scipy
2. pooch

[constantinpape]

That's actually intended: scipy and pooch are only test dependencies, they are not needed for the library itself. But we should point that out in the documentation, so I'll leave this open for now.