Update kube-prometheus-stack Docker tag to v78 (#1720)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [kube-prometheus-stack](https://github.com/prometheus-operator/kube-prometheus) ([source](https://github.com/prometheus-community/helm-charts)) | major | `77.14.0` -> `78.0.0` |

---

### Release Notes

<details>
<summary>prometheus-community/helm-charts (kube-prometheus-stack)</summary>

### [`v78.0.0`](https://github.com/prometheus-community/helm-charts/releases/tag/kube-prometheus-stack-78.0.0)

[Compare Source](https://github.com/prometheus-community/helm-charts/compare/kube-prometheus-stack-77.14.0...kube-prometheus-stack-78.0.0)

kube-prometheus-stack collects Kubernetes manifests, Grafana dashboards, and Prometheus rules combined with documentation and scripts to provide easy to operate end-to-end Kubernetes cluster monitoring with Prometheus using the Prometheus Operator.

#### What's Changed

- \[kube-prometheus-stack] bump to 0.86.0 by [@&#8203;DrFaust92](https://github.com/DrFaust92) in [#&#8203;6211](https://github.com/prometheus-community/helm-charts/pull/6211)

**Full Changelog**: <https://github.com/prometheus-community/helm-charts/compare/prometheus-27.40.0...kube-prometheus-stack-78.0.0>

</details>

---

### 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:eyJjcmVhdGVkSW5WZXIiOiI0MS4xMzUuNCIsInVwZGF0ZWRJblZlciI6IjQxLjEzNS40IiwidGFyZ2V0QnJhbmNoIjoibWFpbiIsImxhYmVscyI6WyJpbWFnZSJdfQ==-->

Reviewed-on: #1720
Co-authored-by: Renovate Bot <renovate-bot@alexlebens.net>
Co-committed-by: Renovate Bot <renovate-bot@alexlebens.net>

clusters/cl01tl/monitoring/kube-prometheus-stack/Chart.yaml

@@ -19,7 +19,7 @@ maintainers:
   - name: alexlebens
 dependencies:
   - name: kube-prometheus-stack
-    version: 77.14.0
+    version: 78.0.0
     repository: oci://ghcr.io/prometheus-community/charts
   - name: app-template
     alias: ntfy-alertmanager