upgrade-api-returns (U1904)

@api.returns, removed in Odoo 19.0.

Applies to Odoo 19.0 and later.

What it does

Reports the @api.returns(...) decorator.

Why is this bad?

Odoo 19.0 removed api.returns without a deprecation period: the module fails to load with AttributeError.

Fix safety

Safe: the decorator line is removed.