Minor release (1.6.0) for validations-common with dedicated stable branch

Creates new release of validations-common to accompany 1.6.0 release
of validations-libs introduced by [0].

The stable branch stable/1.6.0 will serve to facilitate long term
maintenance of the aformentioned release.

[0] https://review.opendev.org/c/openstack/releases/+/825010

Signed-off-by: Jiri Podivin <jpodivin@redhat.com>
Change-Id: Id0a186fba63049b28fb4e6151bcf2dc19c9e2d65

deliverables/_independent/validations-common.yaml

@@ -1,5 +1,6 @@
 ---
 launchpad: tripleo
+stable-branch-type: upstream
 release-type: python-pypi
 team: tripleo
 type: other
@@ -34,4 +35,11 @@ releases:
     projects:
       - repo: openstack/validations-common
         hash: cf7ebddc6a7cf0cdc3d829a3b34e6a3ece587ce3
+  - version: 1.6.0
+    projects:
+      - repo: openstack/validations-common
+        hash: a7ed9c1e88d9de64f5de8715acba188027212ed0
+branches:
+  - name: stable/1.6
+    location: 1.6.0
 release-notes: https://docs.openstack.org/releasenotes/validations-common/ussuri.html