Unnecessary dependencies

[NixBiks]

In setup.cfg the following dependencies are listed

ipython>=6
nbformat>=4
nbconvert>=5
requests>=2

Isn't that a mistake?

I also see Js2Py being used in scxml.py but only listed in requirements_dev.txt. That seems wrong as well.

Let me know if any of this is intended and then I'll fix in a PR.

[davidkpiano]

The setup.cfg dependencies look wrong to me, too. And yes, Js2Py should be included.