Schedule pipeline in release branch (#682)

.azure-pipelines/azure-pipelines-released-version.yml

@@ -4,6 +4,14 @@ pr: none
 
 trigger: none
 
+schedules:
+- cron: "0 0 * * *"
+  displayName: Daily midnight build
+  branches:
+    include:
+    - release-*
+  always: true
+
 jobs:
 
 - job: 'Build_Publish_Azure_CLI_Test_SDK'