chore(deps): update helm release kube-prometheus-stack to v56.9.0 (#386)

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)) | minor | `56.8.2` -> `56.9.0` |

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### Release Notes

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

### [`v56.9.0`](https://github.com/prometheus-community/helm-charts/releases/tag/kube-prometheus-stack-56.9.0)

[Compare Source](prometheus-community/helm-charts@kube-prometheus-stack-56.8.2...kube-prometheus-stack-56.9.0)

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] allow override of for and severity rules by [@&#8203;ps-xaf](https://github.com/ps-xaf) in prometheus-community/helm-charts#4225

#### New Contributors

-   [@&#8203;ps-xaf](https://github.com/ps-xaf) made their first contribution in prometheus-community/helm-charts#4225

**Full Changelog**: prometheus-community/helm-charts@prometheus-blackbox-exporter-8.11.0...kube-prometheus-stack-56.9.0

</details>

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Reviewed-on: https://git.home/nrdufour/home-ops/pulls/386
Co-authored-by: Renovate <[email protected]>
Co-committed-by: Renovate <[email protected]>

kubernetes/main/apps/observability/kube-prometheus-stack/app/helm-release.yaml

@@ -10,7 +10,7 @@ spec:
   chart:
     spec:
       chart: kube-prometheus-stack
-      version: 56.8.2
+      version: 56.9.0
       sourceRef:
         kind: HelmRepository
         name: prometheus-community-charts