fix: missing update verb in hubble-generate-certs

If hubble-ca-secret already exists, then certgen is
going to update it.

To let certgen do its job, we need to configure update
verb in the binded ClusterRole, otherwise it will fail
with cannot update resource \"secrets\" in API group
message.

Fixes: #16508

Signed-off-by: Alex Szakaly <alex.szakaly@gmail.com>

install/kubernetes/cilium/templates/hubble-generate-certs-clusterrole.yaml

@@ -37,4 +37,5 @@ rules:
       - hubble-ca-secret
     verbs:
       - get
+      - update
 {{- end }}