keystone_authtoken/auth_uri is deprecated [1]. Use www_authenticate_uri
instead.
keystonemiddleware is in requirements and lower constraints
should be increased because www_authenticate_uri was introduced
in keystonemiddleware 4.18.0.
[1] https://review.openstack.org/#/c/508522/
Change-Id: Iad00242c629d1a321c5067e705108396931402a2