chore(deps): update helm release kube-prometheus-stack to v56.21.4 (#2187)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

Diff for: charts/selenium-grid/Chart.yaml

@@ -19,7 +19,7 @@ dependencies:
   name: jaeger
   condition: tracing.enabled
 - repository: https://prometheus-community.github.io/helm-charts
-  version: 56.15.0
+  version: 56.21.4
   name: kube-prometheus-stack
   condition: monitoring.enabled
   alias: prometheus-stack