install instructions dont work - scnym won't install with python 3.10 about scnym

[jacobkimmel]

It seems like this is rooted in a couple different issues that arose between 3.8 -> 3.10:

1. An update in setuptools>=38 that breaks support for use_2to3 in project builds. A couple of the common single cell packages haven't updated their build tools to account for this yet (e.g. louvain). https://setuptools.pypa.io/en/latest/history.html#v58-0-0
2. scikit-misc seems to misspecify their build tools for the newest python versions, but I found we could drop the dependency.
3. torch is not yet supported in python=3.10

I've added a note to the README to encourage python=3.8 for users given the torch issues. I'll revisit supporting newer python versions when major dependencies add support.

Addressed in #18