Upgrading kubernetes API

Change-Id: I279db986e2dab1ebcb5b48b4195363af395c8de3
diff --git a/nem-monitoring/requirements.yaml b/nem-monitoring/requirements.yaml
index be9439f..e0851e2 100644
--- a/nem-monitoring/requirements.yaml
+++ b/nem-monitoring/requirements.yaml
@@ -16,7 +16,7 @@
 dependencies:
 - name: prometheus
   version: 9.3.1
-  repository: https://kubernetes-charts.storage.googleapis.com/
+  repository: https://charts.helm.sh/stable
 - name: grafana
   version: 4.0.2
-  repository: https://kubernetes-charts.storage.googleapis.com/
+  repository: https://charts.helm.sh/stable