Remove scipy (unused)

[josephrocca]

You may have wanted to leave this in for some reason, in which case feel free to close this pull request. This would mainly be desirable for me to make the Colab demo easier, but it's no big deal.

Edit: I notice that matplotlib isn't used either - and now that I think about it, I'm guessing it's just used for debugging? Maybe you'd prefer to leave those dependencies in for that reason.