kube-prometheus: Update grafana jsonnet dependency

manifests/grafana-dashboardDatasources.yaml

@@ -2,12 +2,13 @@ apiVersion: v1
 data:
   prometheus.yaml: |-
     {
+        "apiVersion": 1,
         "datasources": [
             {
                 "access": "proxy",
                 "editable": false,
                 "name": "prometheus",
-                "org_id": 1,
+                "orgId": 1,
                 "type": "prometheus",
                 "url": "http://prometheus-k8s.monitoring.svc:9090",
                 "version": 1