chore(deps): update helm release prometheus-community/prometheus to v28.15.0

Author: renovate[bot]

examples/prometheus-grafana.yaml

@@ -11,7 +11,7 @@ spec:
   - repositoryURL:    https://prometheus-community.github.io/helm-charts
     repositoryName:   prometheus-community
     chartName:        prometheus-community/prometheus
-    chartVersion:     28.14.1
+    chartVersion:     28.15.0
     releaseName:      prometheus
     releaseNamespace: prometheus
     helmChartAction:  Install