check in CheckConstraint should support expression

[littlebtc]

Bug report

What's wrong

As of Django 3.1 (#30484), the CheckConstraint supports Q and boolean Expression, but only Q is allowed in current type stubs.

By following it is the code snippets from tests/constraints/models.py that will throw typing error:

            models.CheckConstraint(
                check=models.expressions.RawSQL(
                    "price < %s", (1000,), output_field=models.BooleanField()
                ),
                name="%(app_label)s_price_lt_1000_raw",
            ),
            models.CheckConstraint(
                check=models.expressions.ExpressionWrapper(
                    models.Q(price__gt=500) | models.Q(price__lt=500),
                    output_field=models.BooleanField(),
                ),
                name="%(app_label)s_price_neq_500_wrap",
            ),

How is that should be

Maybe like #806, make check accepts Union[Q, Combinable].

System information

• OS: Debian 11
• python version: 3.9
• django version: 3.2
• mypy version: 0.931
• django-stubs version: 1.9.0
• django-stubs-ext version: 0.3.1