sklearn dependancy in setup.py should be scikit-learn

[gsbowlin]

When installing locally, it looks like the setup.py is incorrectly listing dependencies resulting in the following pip list

scikit-learn 0.24.20 <-- Already installed before installing zEpid
sklearn 0.0 <-- added after installing zEpid, but not really sklearn.

The first is the correct package, but the second is very out of date.

See the pypi reference for sklearn: https://pypi.org/project/sklearn/

[pzivich]

thanks! that is my mistake. Will fix