chore(deps): update postgres-cluster docker tag to v7.8.0 (#4278)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [postgres-cluster](https://github.com/cloudnative-pg/cloudnative-pg) | minor | `7.7.0` → `7.8.0` |

---

### Configuration

📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied.

♻ **Rebasing**: Whenever PR is behind base branch, or you tick the rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about this update again.

---

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

---

This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).
<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiI0My4yNS43IiwidXBkYXRlZEluVmVyIjoiNDMuMjUuNyIsInRhcmdldEJyYW5jaCI6Im1haW4iLCJsYWJlbHMiOlsiY2hhcnQiLCJpbWFnZSJdfQ==-->

Reviewed-on: #4278
Co-authored-by: Renovate Bot <renovate-bot@alexlebens.net>
Co-committed-by: Renovate Bot <renovate-bot@alexlebens.net>

clusters/cl01tl/helm/argo-workflows/Chart.lock

@@ -7,6 +7,6 @@ dependencies:
   version: 2.4.20
 - name: postgres-cluster
   repository: oci://harbor.alexlebens.net/helm-charts
-  version: 7.7.0
-digest: sha256:aab605d619f2f5940f84f61f60cdc41c7c8d786d0c870e0162168dcfa3ad3d6e
-generated: "2026-02-21T13:54:24.776115-06:00"
+  version: 7.8.0
+digest: sha256:772ba83a6e0fa6a7e3633ff1fff0f8221b45a1f36ec890489cfa383330d99f81
+generated: "2026-02-27T18:14:32.22595048Z"