chore: Update oslo.config to version 1.2.0a4
chore: Update oslo.config to version 1.2.0a4

Change-Id: I7bbf9ff4b7a9375f51e49e348ea60e723fdde276

openstack/zaqar,openstack/zaqar,openstack/zaqar,openstack/zaqar,rackerlabs/marconi