Update postgres-cluster Docker tag to v6.16.1 (#2237)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [postgres-cluster](https://github.com/cloudnative-pg/cloudnative-pg) | patch | `6.16.0` -> `6.16.1` |

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### Configuration

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Reviewed-on: #2237
Co-authored-by: Renovate Bot <renovate-bot@alexlebens.net>
Co-committed-by: Renovate Bot <renovate-bot@alexlebens.net>

clusters/cl01tl/helm/stalwart/Chart.lock

@@ -4,6 +4,6 @@ dependencies:
   version: 4.4.0
 - name: postgres-cluster
   repository: oci://harbor.alexlebens.net/helm-charts
-  version: 6.16.0
-digest: sha256:88a8c0f96b046372d76ae0ebdd3f2fd2a5bc049eba3c145832a3c1c8704dc1bb
-generated: "2025-12-01T20:27:35.237977-06:00"
+  version: 6.16.1
+digest: sha256:87a9e98c0de182dec42160186a57ced84a62782c9a84fe0dbea56789de9606bf
+generated: "2025-12-04T00:06:09.631961901Z"