Update kube-prometheus-stack chart to 19.0.0

Related: #833

flux2/apps/monitoring/kube-prometheus-stack-release.yaml

@@ -8,8 +8,9 @@ spec:
   releaseName: kube-prometheus-stack
   chart:
     spec:
+      # https://artifacthub.io/packages/helm/prometheus-community/kube-prometheus-stack
       chart: kube-prometheus-stack
-      version: 18.0.12
+      version: 19.0.0
       sourceRef:
         kind: HelmRepository
         name: prometheus-community
@@ -32,4 +33,3 @@ spec:
     - kind: Secret
       name: oas-kube-prometheus-stack-override
       optional: true
-