Don't perform cart update on search submit

If you have a search widget on the cart page which is wrapped in a div
(the default wrapper for widgets) the ajax cart would try to update on
search submit. This change ensures the search form is excluded on
`submit_click`.

assets/js/frontend/cart.js

@@ -275,7 +275,7 @@ jQuery( function( $ ) {
 				this.submit_click );
 			$( document ).on(
 				'submit',
-				'div.woocommerce > form',
+				'div.woocommerce:not(.widget_product_search) > form',
 				this.cart_submit );
 			$( document ).on(
 				'click',