removed argument no longer valid in setuptools >=58

[tyler-jachetta]

This PR makes setup.py valid in environments with setuptools >= v58

[tyler-jachetta]

@parsifal-47 see you're kinda active here. This would solve a headache for me if you can find a way to get this in :)

[parsifal-47]

@tyler-jachetta unfortunately, my permissions to merge at this repo have been revoked long time ago, not sure what I can do now

[parsifal-47]

thanks a lot @twonds!