[Tempest Plugins] Tag stein-last

Stein branch is in Extended Maintenance now[1]. All Tempest
plugins are branchless which means master version of Tempest
and its plugins is used to test the supported stable branches.

Once stable branch is moved to EM state then, Tempest and its
plugins compatible tag needs to be released so that we can
keep testing the EM stable branches with this tag once master
Tempest and its plugins are not compatible[2].

This tag will help for testing the stable/stein with single
compatible tag of Tempest and its plugins.

Tagging 'stein-last' as well as a new version also with same hash.
Documenting this new tag name here
- https://review.opendev.org/c/openstack/project-team-guide/+/769821

More detail on compatible version policy for Tempest and its
plugins is here
- https://docs.openstack.org/tempest/latest/tempest_and_plugins_compatible_version_policy.html

[1] https://releases.openstack.org/stein/index.html
[2] https://docs.openstack.org/tempest/latest/stable_branch_support_policy.html

Change-Id: I3dedf43f254a745684014bc050ff6ac399144b06

deliverables/stein/heat-tempest-plugin.yaml

@@ -12,3 +12,7 @@ releases:
       - hash: f543d390e187975ff8002f1817de8509466b80aa
         repo: openstack/heat-tempest-plugin
     version: 0.3.0
+  - version: stein-last
+    projects:
+      - repo: openstack/heat-tempest-plugin
+        hash: c5e1603fb62a8e2e18706c6c084d0fa2a908dad8

deliverables/wallaby/heat-tempest-plugin.yaml

@@ -8,3 +8,8 @@ repository-settings:
   openstack/heat-tempest-plugin: {}
 team: heat
 type: tempest-plugin
+releases:
+  - version: 1.2.0
+    projects:
+      - repo: openstack/heat-tempest-plugin
+        hash: c5e1603fb62a8e2e18706c6c084d0fa2a908dad8