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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 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box

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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/matrix-synapse/Chart.lock

@@ -13,6 +13,6 @@ dependencies:
   version: 1.23.1
 - name: postgres-cluster
   repository: oci://harbor.alexlebens.net/helm-charts
-  version: 6.16.0
-digest: sha256:bad19cd53e51ab6ba04afc9b73e768fcf755562fabf17866a826207816fd53d1
-generated: "2025-12-03T06:04:00.067196405Z"
+  version: 6.16.1
+digest: sha256:1bf6e5f4693930d4f0ee8753eae5afee055894f01ddbefbae969bf834c8cad99
+generated: "2025-12-04T00:02:43.058364936Z"