[FIX] stock: incorrect field
[FIX] stock: incorrect field

The field is now `quantity`. This wasn't spotted before because the
method is not used anywhere.

opw-2008491

closes odoo/odoo#34067

Signed-off-by: Nicolas Martinelli (nim) <771435c469f83f6aa9c405ac5e1ed06314a94f2d@odoo.com>
ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo