[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: I3c4ad43a9e878ac4d749f8a96c36a3da24d121e9

deliverables/stein/magnum-tempest-plugin.yaml

@@ -13,3 +13,7 @@ releases:
       - hash: 72a29d8e43daaa03b00d50358b4088e7f60fb859
         repo: openstack/magnum-tempest-plugin
     version: 0.2.0
+  - version: stein-last
+    projects:
+      - repo: openstack/magnum-tempest-plugin
+        hash: 487571aa0cc5854c5101485763abeb5cf959f1fd

deliverables/wallaby/magnum-tempest-plugin.yaml

@@ -9,3 +9,8 @@ repository-settings:
     tarball-base: magnum_tempest_plugin
 team: magnum
 type: tempest-plugin
+releases:
+  - version: 1.2.0
+    projects:
+      - repo: openstack/magnum-tempest-plugin
+        hash: 487571aa0cc5854c5101485763abeb5cf959f1fd