[FIX] stock: display assign SN immediate transfer

Before this commit, when user creates a receipt for a product tracked by
serial number, using immediate transfer, the fields to generate and
assign SN was hidden.
The reason was the move is confirmed in this case, and those fields was
displayed only for partially available and assigned moves.

task-2123761

X-original-commit: 4f9b170e857509cf34e072051086a7e9590c330d

addons/stock/models/stock_move.py

@@ -187,7 +187,7 @@ class StockMove(models.Model):
         for move in self:
             move.display_assign_serial = (
                 move.has_tracking == 'serial' and
-                move.state in ('partially_available', 'assigned') and
+                move.state in ('partially_available', 'assigned', 'confirmed') and
                 move.picking_type_id.use_create_lots and
                 not move.picking_type_id.use_existing_lots and
                 not move.picking_type_id.show_reserved