Allow modifications of incoterm until customer's shipments has been shipped

Closes #14203

modules/incoterm/CHANGELOG

@@ -1,3 +1,4 @@
+* Allow modifications of incoterm until customer's shipments has been shipped
 
 Version 7.6.0 - 2025-04-28
 --------------------------

modules/incoterm/stock.py

@@ -79,6 +79,10 @@ class ShipmentInReturn(ShipmentMixin, metaclass=PoolMeta):
 class ShipmentOut(ShipmentMixin, metaclass=PoolMeta):
     __name__ = 'stock.shipment.out'
 
+    @classmethod
+    def _incoterm_readonly_state(cls):
+        return Eval('state').in_(['cancelled', 'shipped,' 'done'])
+
     @classmethod
     def _incoterm_related_party(cls):
         return Eval('customer'), {'customer'}