Tag stable/stein tripleo repos as EOL

As discussed at [1] this tags the last commits to the
stable/stein branch as stein-eol for tripleo repos [2]

[1] http://lists.openstack.org/pipermail/openstack-discuss/2021-June/023115.html
[2] https://releases.openstack.org/teams/tripleo.html#stein

Change-Id: I6d6488b2a02f27f58d59be35aa1dc7a178fe15f2

deliverables/stein/tripleo-validations.yaml

@@ -43,6 +43,10 @@ releases:
     projects:
       - repo: openstack/tripleo-validations
         hash: 730ef1ff02d8013fc429cc4794dda96e6c254aa7
+  - version: stein-eol
+    projects:
+      - repo: openstack/tripleo-validations
+        hash: 595eec78ff33a82f0a1295601bf44b9e4482a428
 branches:
   - location: 10.4.0
     name: stable/stein