chore(helm): update image ghcr.io/cloudnative-pg/postgresql 16.4 → 16.6 (#31496)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| ghcr.io/cloudnative-pg/postgresql | minor |  ->  |

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charts/library/common/Chart.yaml

@@ -48,4 +48,4 @@ sources:
   - https://hub.docker.com/_/
   - https://hub.docker.com/r/mikefarah/yq
 type: library
-version: 25.4.14
+version: 25.5.0

charts/library/common/values.yaml

@@ -544,7 +544,7 @@ postgres15Image:
 
 postgres16Image:
   repository: ghcr.io/cloudnative-pg/postgresql
-  tag: "16.4"
+  tag: "16.6"
   pullPolicy: IfNotPresent
 
 postgresPostgis15Image: