chore: add secrets RBAC permission to helm chart

Required to support reading CODER_AGENT_TOKEN from Kubernetes secrets
via secretKeyRef.

Author: kacpersaw

helm/templates/service.yaml

@@ -2,6 +2,9 @@
 - apiGroups: [""]
   resources: ["pods", "events"]
   verbs: ["get", "watch", "list"]
+- apiGroups: [""]
+  resources: ["secrets"]
+  verbs: ["get"]
 - apiGroups: ["apps"]
   resources: ["replicasets", "events"]
   verbs: ["get", "watch", "list"]