[FIX] account_ebics - Wrap order number ZZZZ to A000

ZZZZ is accepted by the order number constraint, but the next number was
computed as 0000, which the constraint then rejects, blocking H003
uploads. Wrap it to A000 like ZZZY already does.

account_ebics/models/ebics_config.py

@@ -188,7 +188,7 @@ class EbicsConfig(models.Model):
             o_list[-i] = chr(ord(c) + 1)
             break
         next_order_number = "".join(o_list)
-        if next_order_number == "ZZZZ":
+        if "ZZZZ" in (OrderID, next_order_number):
             next_order_number = "A000"
         self.order_number = next_order_number