Fix accidential removal of gitcard-filter

src/pretix/base/exporters/orderlist.py

@@ -662,6 +662,7 @@ class GiftcardRedemptionListExporter(ListExporter):
     def iterate_list(self, form_data):
         payments = OrderPayment.objects.filter(
             order__event__in=self.events,
+            provider='giftcard',
             state__in=(OrderPayment.PAYMENT_STATE_CONFIRMED, OrderPayment.PAYMENT_STATE_REFUNDED),
         ).order_by('created')
         refunds = OrderRefund.objects.filter(