Fix a g++-9 warning

Quite a strange warning: suggested parenthesis in a Catch2 macro
expansion

tests/test_SubItemValuePerItem.cpp

@@ -63,7 +63,8 @@ TEST_CASE("SubItemValuePerItem", "[mesh]")
     };
 
     auto check_same_memory = [](const auto& sub_item_value_per_item, auto array) {
-      REQUIRE(sub_item_value_per_item.numberOfValues() == array.size());
+      const bool same_size = (sub_item_value_per_item.numberOfValues() == array.size());
+      REQUIRE(same_size);
       bool is_same = true;
       for (size_t i = 0; i < sub_item_value_per_item.numberOfValues(); ++i) {
         is_same &= (&(sub_item_value_per_item[i]) == &(array[i]));