Add release branch sync workflow

Author: abays

.github/workflows/release-branch-sync.yaml

@@ -0,0 +1,13 @@
+---
+name: Release Branch sync
+
+on:  # yamllint disable-line rule:truthy
+  push:
+    branches:
+      - '*'
+  schedule:
+    - cron: '0 * * * *'
+
+jobs:
+  call-build-workflow:
+    uses: openstack-k8s-operators/openstack-k8s-operators-ci/.github/workflows/release-branch-sync.yaml@main