[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: Ifca7509336bdc087f87519a290a768f50d68edb8

deliverables/stein/oswin-tempest-plugin.yaml

@@ -12,3 +12,7 @@ releases:
       - hash: df19edfc31f716ea21b4bde04f6661e81d603ff7
         repo: openstack/oswin-tempest-plugin
     version: 0.2.0
+  - version: stein-last
+    projects:
+      - repo: openstack/oswin-tempest-plugin
+        hash: 4e2b705bc082997faed1df412b798a843ca4937d

deliverables/wallaby/oswin-tempest-plugin.yaml

@@ -8,3 +8,8 @@ repository-settings:
   openstack/oswin-tempest-plugin: {}
 team: winstackers
 type: tempest-plugin
+releases:
+  - version: 1.2.0
+    projects:
+      - repo: openstack/oswin-tempest-plugin
+        hash: 4e2b705bc082997faed1df412b798a843ca4937d