Fix default where clause order to work with new format

[drewbaker]

It looks like they changed the format for the ORDER where clauses.

It used to be this:
https://github.com/funkhaus/fuxt-backend/blob/master/functions/gql-functions.php#L532-L533

But now it needs to be like this:

            children(
                where: {
                    orderby: { field: MENU_ORDER, order: ASC }
                }
            ) {

[rsm0128]

Hi Drew,
I checked the wp-graphql repository, but there is no recent change with the orderby format.
Also, I checked both of the code in wp-graphql and fuxt-backend and it seems fine.
Or did I miss something?