make Refilling.payment_method a SmallIntegerField

eboutic/models.py

@@ -253,7 +253,7 @@ class Invoice(models.Model):
                     customer=customer,
                     operator=self.user,
                     amount=i.product_unit_price * i.quantity,
-                    payment_method="CARD",
+                    payment_method=Refilling.PaymentMethod.CARD,
                     date=self.date,
                 )
                 new.save()

eboutic/views.py

@@ -275,7 +275,9 @@ class EbouticPayWithSith(CanViewMixin, SingleObjectMixin, View):
             return redirect("eboutic:payment_result", "failure")
 
         eboutic = get_eboutic()
-        sales = basket.generate_sales(eboutic, basket.user, Selling.PaymentMethod.SITH_ACCOUNT)
+        sales = basket.generate_sales(
+            eboutic, basket.user, Selling.PaymentMethod.SITH_ACCOUNT
+        )
         try:
             with transaction.atomic():
                 # Selling.save has some important business logic in it.