Update .coveragerc after the removal of openstack directory
Update .coveragerc after the removal of openstack directory

The openstack directory was used to keep codes from oslo-incubator,
we have retired oslo-incubator,so don't use this directory any more.

Change-Id: Ifcf1a4388bd886d5d04675a54112857d99d43586

openstack-dev/pbr,openstack-dev/pbr,openstack-dev/pbr