Make sure to *not* undeclare the liveliness token for clients. (#219)

That is, we were forgetting to cancel the undeclare of
the liveliness token in client initialization, so we
would create the token and immediately remove it.  Fix
that here, so it only gets removed at rmw_destroy_client
time.

Signed-off-by: Chris Lalancette <[email protected]>

rmw_zenoh_cpp/src/rmw_zenoh.cpp

@@ -2235,6 +2235,7 @@ rmw_create_client(
 
   rmw_client->data = client_data;
 
+  free_token.cancel();
   free_rmw_client.cancel();
   free_client_data.cancel();
   destruct_request_type_support.cancel();