Add Patrole gate job for stable/stein

Now we have stable/stein branch ready for devstack
and so does for all service projects.

This commit adds the Project testing for stable/stein
by adding new jobs running on stable/stein version of
openstack.
Depends-On: https://review.openstack.org/#/c/647867/

Change-Id: I180d1133b4b77ee7aeff596899f9d7ad9b6d14fe
diff --git a/.zuul.yaml b/.zuul.yaml
index 9c2925d..957ede3 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -94,6 +94,11 @@
         RBAC_TEST_ROLES: reader
 
 - job:
+    name: patrole-member-stein
+    parent: patrole-member
+    override-checkout: stable/stein
+
+- job:
     name: patrole-member-rocky
     nodeset: openstack-single-node-xenial
     parent: patrole-member
@@ -204,6 +209,7 @@
         - patrole-admin
         - patrole-member
         - patrole-reader
+        - patrole-member-stein
         - patrole-member-rocky
         - patrole-member-queens
         - patrole-member-pike
@@ -218,6 +224,7 @@
         - patrole-member
     periodic-stable:
       jobs:
+        - patrole-member-stein
         - patrole-member-rocky
         - patrole-member-queens
         - patrole-member-pike