pip provider doesn't handle arbitrary equality

Puppet Version: 5.5.6
Puppet Server Version: 5.3.5
OS Name/Version: Ubuntu 18.04

The current pip provider doesn't support Python's arbitrary equality https://www.python.org/dev/peps/pep-0440/#arbitrary-equality

When encountering a python package specified with arbitrary equality via pip freeze, it fails to parse the package and keeps trying to install it

e.g.

$ pip freeze | grep pytz

pytz===2012f

Desired Behavior: Pip Provider correctly handles arbitrary equality

Actual Behavior: Pip Provider incorrectly handles arbitrary equality