fix weight error in tarnsaction validation serializer

apps/warehouse/pos/api/v1/serializers.py

@@ -182,7 +182,7 @@ class InventoryQuotaSaleTransactionSerializer(serializers.ModelSerializer):
                     total=models.Sum('weight')
                 )['total'] or 0
 
-                if total_sale_weight + attrs['weight'] > distribution.weight:
+                if total_sale_weight + item.get('weight') > distribution.weight:
                     raise DistributionWeightException()
 
         return attrs