feat(container): update image docker.io/bitnami/postgresql to v15.6.0

| datasource | package                      | from   | to     |
| ---------- | ---------------------------- | ------ | ------ |
| docker     | docker.io/bitnami/postgresql | 15.5.0 | 15.6.0 |

cluster/apps/databases/postgresql/helm-release.yaml

@@ -37,7 +37,7 @@ spec:
     image:
       registry: docker.io
       repository: bitnami/postgresql
-      tag: "15.5.0"
+      tag: "15.6.0"
     primary:
       persistence:
         enabled: true