[stable/datadog] Grant access to kubelet’s GET /stats/summary (#19047)

With DataDog/integrations-core#5052, the datadog agent starts monitoring
the `stats/summary/` endpoint of the kubelet.
So, we need to grant it a role that allows it.

Signed-off-by: Lénaïc Huard <lenaic.huard@datadoghq.com>

stable/datadog/Chart.yaml

@@ -1,6 +1,6 @@
 apiVersion: v1
 name: datadog
-version: 1.38.3
+version: 1.38.4
 appVersion: 6.14.0
 description: DataDog Agent
 keywords:

stable/datadog/templates/rbac.yaml

@@ -78,6 +78,7 @@ rules:
   - nodes/metrics
   - nodes/spec
   - nodes/proxy
+  - nodes/stats
   verbs:
   - get
 - apiGroups:  # leader election check