Add missing pod/container flags to alerta

Adding runAsUser and readOnly-fs flag to alerta pod/container.

The security context templates are added here:
https://github.com/openstack/openstack-helm-infra/blob/master/alerta/templates/deployment.yaml#L52

Change-Id: I1136f776ffd7caf54310288a162563ef4e565bbe

alerta/Chart.yaml

@@ -15,7 +15,7 @@ apiVersion: v1
 appVersion: v8.0.2
 description: OpenStack-Helm Alerta for Alertmanager.
 name: alerta
-version: 0.1.3
+version: 0.1.4
 home: https://github.com/alerta/alerta
 sources:
   - https://github.com/alerta/alerta

alerta/values.yaml

@@ -72,6 +72,12 @@ pod:
         postgresql_create_db:
           readOnlyRootFilesystem: true
           allowPrivilegeEscalation: false
+    server:
+      pod:
+        runAsUser: 0
+      container:
+        alerta:
+          readOnlyRootFilesystem: false
   affinity:
     anti:
       type: