[fix] Add delay for date_due in subscritions_invoices

coin/billing/create_subscriptions_invoices.py

@@ -47,7 +47,7 @@ def create_member_invoice_for_a_period(member, date):
                           relativedelta(days=+1))
 
     invoice = Invoice.objects.create(
-        date_due=datetime.date.today(),
+        date_due=datetime.date.today() + datetime.timedelta(days=settings.PAYMENT_DELAY),
         member=member
     )