Add label for single function query

Adding label when a /system/function/<name> endpoint
is invoked as it was missed in the previous commit

Signed-off-by: Martin Dekov <mvdekov@gmail.com>

pkg/provider/handlers/replicas.go

@@ -21,6 +21,7 @@ func MakeReplicaReaderHandler(client *containerd.Client) func(w http.ResponseWri
 				AvailableReplicas: uint64(f.replicas),
 				Replicas:          uint64(f.replicas),
 				Namespace:         f.namespace,
+				Labels:            &f.labels,
 			}
 
 			functionBytes, _ := json.Marshal(found)