Depends on zipp, but the newer zipp versions don't work on Python2

I realize python2 is out of support so maybe no one cares but: many things depend on importlib-metadata and importlib-metadata depends on zipp:

install_requires =
        zipp>=0.5
        pathlib2; python_version < '3'
        contextlib2; python_version < '3'
        configparser>=3.5; python_version < '3'

However, any version of zipp over 1.1.1 requires Python3, so this set of requires causes failures on Python2. I don't know if it's sufficient to add the python_version to the zipp line or if more is needed.