Fix UB

Signed-off-by: Yadunund <[email protected]>

rmw_zenoh_cpp/src/detail/liveliness_utils.cpp

@@ -224,7 +224,7 @@ std::string zid_to_str(const z_id_t & id)
   std::stringstream ss;
   ss << std::hex;
   // By Zenoh convention a z_id_t is a little endian u128
-  size_t i = sizeof(id.id) - 1;
+  int i = static_cast<int>(sizeof(id.id) - 1);
   for (; i >= 0; i--) {
     ss << static_cast<int>(id.id[i]);
   }