spec: Require python-pbr
spec: Require python-pbr

We forgot to update .spec Requires for pbr in efc76e8.

Change-Id: I050d83d5da6e8b77ed5306cb87b0ac720457d8c9

redhat-openstack/rdopkg,openstack-packages/rdopkg,openstack-packages/rdopkg,redhat-openstack/rdopkg