chore(deps): update helm release grafana-operator to v5.21.4 (#40)

Co-authored-by: monkescience-renovate[bot] <212128645+monkescience-renovate[bot]@users.noreply.github.com>

Author: monkescience-renovate[bot]

apps/eu-central-1-dev/platform/grafana.yaml

@@ -12,7 +12,7 @@ spec:
   sources:
     - repoURL: https://grafana.github.io/helm-charts
       chart: grafana-operator
-      targetRevision: 5.21.3
+      targetRevision: 5.21.4
       helm:
         valueFiles:
           - $values/manifests/grafana-operator/eu-central-1-dev/values.yaml