Fix: Rare case where after bill is printed and nother kot added, the void bill kots have same time and a wrong kot can be printed.

This orders the kots by code, not time and so should take care of the issue

barker/barker/models/voucher.py

@@ -52,7 +52,7 @@ class Voucher(Base):
         backref="voucher",
         cascade="delete, delete-orphan",
         cascade_backrefs=False,
-        order_by=Kot.date,
+        order_by=Kot.code,
     )
     settlements = relationship(
         "Settlement",