Remove pypy env from tox
Remove pypy env from tox

We removed pypy's gate a few weeks ago as it's been failing for some
time. This means we're not supporting it anymore. Therefore, it should
be ok to remove it from the tox file.

Change-Id: Iac9bf4775794b8d097c0c5cae0337f14fa2fa25c

openstack/python-glanceclient,klmitch/python-glanceclient,openstack/python-glanceclient,klmitch/python-glanceclient