[FIX] mrp: manufacture user can not record production

Usecase to reproduce:
- Connect with demo user
- Create a MO w/h routing
- Confirm and produce it
- Record the production wizard

Access right error on product.product for field tracking

It happens because the wizard use a related to product.tracking howerver
it is not set as readonly on the view and send to the server as a value
on save. Since it write on a related field it will try to write on the
linked model(product.product).

This commit set the field as readonly so it is not set to the server.
The field is just used inside domain and it is invisible to the user
so it do not modify any behavior.

opw-1918684

closes odoo/odoo#29942

addons/mrp/wizard/mrp_product_produce.py

@@ -85,7 +85,7 @@ class MrpProductProduce(models.TransientModel):
     product_uom_id = fields.Many2one('product.uom', 'Unit of Measure')
     lot_id = fields.Many2one('stock.production.lot', string='Lot')
     produce_line_ids = fields.One2many('mrp.product.produce.line', 'product_produce_id', string='Product to Track')
-    product_tracking = fields.Selection(related="product_id.tracking")
+    product_tracking = fields.Selection(related="product_id.tracking", readonly=True)
 
     @api.multi
     def do_produce(self):