Add missed PrettyTable requirement
Add missed PrettyTable requirement

Change-Id: Ibd4f9c84b08809a8a3a75b104dfa2419ac5182a3

citrix-openstack-build/python-saharaclient,openstack/python-saharaclient,citrix-openstack-build/python-saharaclient,citrix-openstack-build/python-saharaclient