New rule: check constraints can not have subqueries

[obbteam]

Context:
Just found out that subqueries can not be used in the check constraint.
Squawk linter does not complain but Postgresql throws the following error:
ERROR: cannot use subquery in check constraint (SQLSTATE 0A000)

Example:

ALTER TABLE
	table_x
ADD
	CONSTRAINT bar_should_equal_to_banana CHECK (
		(
			SELECT
				bar
			FROM
				table_y
			WHERE
				table_y.pk = table_x.y_pk
		) = 'banana'
	);

Expected fix:
New rule should throw an error on subqueries used in the check constraint.
Should suggest to use triggers instead?