[postgresql] Set update strategy to Recreate. (#6343)

* [postgresql] Set update strategy to Recreate.

We NEVER want two different postgres instances to be up at the same time using the same database files, or corruption can occur.
At the cost of having a few seconds of downtime at upgrade time.

* Update Chart.yaml

stable/postgresql/Chart.yaml

@@ -1,5 +1,5 @@
 name: postgresql
-version: 0.14.4
+version: 0.15.0
 appVersion: 9.6.2
 description: Object-relational database management system (ORDBMS) with an emphasis on extensibility and on standards-compliance.
 keywords:

stable/postgresql/templates/deployment.yaml

@@ -20,6 +20,8 @@ spec:
     matchLabels:
       app: {{ template "postgresql.name" . }}
       release: {{ .Release.Name }}
+  strategy:
+    type: Recreate
   template:
     metadata:
       labels: