[mistral-tempest-plugin] Tag train-last

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

Once any stable branch is moved to EM state then, Tempest and
its plugins compatible tag[2] needs to be released so that we can
keep testing the EM stable branches with that tag once master
Tempest and its plugins are not compatible[3].

Tagging 'train-last'[4] as well as a new version also with same hash.

[1] https://releases.openstack.org/train/index.html
[2] https://docs.openstack.org/tempest/latest/stable_branch_support_policy.html
[3] https://docs.openstack.org/tempest/latest/tempest_and_plugins_compatible_version_policy.html
[4] https://docs.openstack.org/project-team-guide/stable-branches.html#extended-maintenance

Change-Id: Iad6f4a21cf7f35f56420b61c1af05e0603075c95

deliverables/train/mistral-tempest-plugin.yaml

@@ -13,3 +13,7 @@ releases:
     projects:
       - repo: openstack/mistral-tempest-plugin
         hash: 3c3a6cc2a13952d763164cced53074482d3f5b8e
+  - version: train-last
+    projects:
+      - repo: openstack/mistral-tempest-plugin
+        hash: 091926bbb405bf8d0249156f11f090dc455077dc

deliverables/xena/mistral-tempest-plugin.yaml

@@ -9,3 +9,8 @@ repository-settings:
     tarball-base: mistral_tempest_tests
 team: mistral
 type: tempest-plugin
+releases:
+  - version: 1.3.0
+    projects:
+      - repo: openstack/mistral-tempest-plugin
+        hash: 091926bbb405bf8d0249156f11f090dc455077dc