Make coupon valid for several categories

If you place a product in category A in Modified and link it in categories B and C - which makes more sense than duplicating it -
and then create a coupon that is valid for category B,
then this product will NOT be taken into account, i.e. although the product can be seen in category B,
you cannot use the coupon code for it.

Through this change, the shop will in future query all categories in which the product is located and accordingly you can also use the code, even though the product was only linked there.