portable: Fix memory leak in maybe_enable_disable()

Fixes #23481

src/portable/portablectl.c

@@ -579,7 +579,9 @@ static int maybe_enable_disable(sd_bus *bus, const char *path, bool enable) {
                 if (r < 0)
                         return bus_log_parse_error(r);
         }
+
         (void) bus_deserialize_and_dump_unit_file_changes(reply, arg_quiet, &changes, &n_changes);
+        unit_file_changes_free(changes, n_changes);
 
         return 0;
 }