chore(deps): update postgres-cluster docker tag to v7.9.1 (#4639)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [postgres-cluster](https://github.com/cloudnative-pg/cloudnative-pg) | minor | `7.8.0` → `7.9.1` |

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<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiI0My41OS4yIiwidXBkYXRlZEluVmVyIjoiNDMuNTkuMiIsInRhcmdldEJyYW5jaCI6Im1haW4iLCJsYWJlbHMiOlsiY2hhcnQiLCJpbWFnZSJdfQ==-->

Reviewed-on: #4639
Co-authored-by: Renovate Bot <renovate-bot@alexlebens.net>
Co-committed-by: Renovate Bot <renovate-bot@alexlebens.net>

clusters/cl01tl/helm/postiz/Chart.lock

@@ -7,7 +7,7 @@ dependencies:
   version: 2.4.0
 - name: postgres-cluster
   repository: oci://harbor.alexlebens.net/helm-charts
-  version: 7.8.0
+  version: 7.9.1
 - name: valkey
   repository: oci://harbor.alexlebens.net/helm-charts
   version: 0.4.0
@@ -17,5 +17,5 @@ dependencies:
 - name: volsync-target
   repository: oci://harbor.alexlebens.net/helm-charts
   version: 0.8.0
-digest: sha256:219e5c5fc45cba34092606802cf1024d99325d8af71d07bbb8758899c0ad5a8f
-generated: "2026-03-09T23:08:31.811042987Z"
+digest: sha256:cf9b71f29450c69550b0f59d792193788f9dd7ffa2c623db27eb423c0f6e3109
+generated: "2026-03-11T23:00:37.739141183Z"