fixes memory leak in routine check_weight_file

tests/weight_file_common.c

@@ -526,6 +526,7 @@ void check_weight_file(char const * file_name, int const * ref_src_address,
   }
 
   // clean up
+  free(str_version);
   free(fixed_values);
   free(num_tgt_per_fixed_value);
   free(tgt_address_fixed);