Add search context fields to purchase line product depends

They should be added explicity because they are not included in display_depends
nor edition_depends

Closes #12407

modules/purchase/purchase.py

@@ -1124,7 +1124,8 @@ class Line(sequence_ordered(), ModelSQL, ModelView):
             'taxes': Eval('taxes', []),
             'quantity': Eval('quantity'),
             },
-        depends={'company'})
+        depends={
+            'company', 'warehouse', 'purchase_date', 'currency', 'supplier'})
     product_supplier = fields.Many2One(
         'purchase.product_supplier', "Supplier's Product",
         ondelete='RESTRICT',