chore(deps): update helm release kube-prometheus-stack to v81.6.9

Author: renovate[bot]

clusters/home-cluster/monitoring/helmrelease.yaml

@@ -10,7 +10,7 @@ spec:
     spec:
       # renovate: registryUrl=https://prometheus-community.github.io/helm-charts
       chart: kube-prometheus-stack
-      version: 81.4.2
+      version: 81.6.9
       sourceRef:
         kind: HelmRepository
         name: prometheus-community