Update Helm release kube-prometheus-stack to v78.4.0

Author: renovate[bot]

fleet/lib/kube-prometheus-stack/fleet.yaml

@@ -8,7 +8,7 @@ helm:
   chart: *name
   releaseName: *name
   repo: https://prometheus-community.github.io/helm-charts
-  version: 78.3.2
+  version: 78.4.0
   timeoutSeconds: 600
   waitForJobs: true
   valuesFiles: