[IMP] stock: add index on the serial name

In large database with unique serial number. The index add performance.

closes odoo/odoo#78024

Signed-off-by: William Henrotin <Whenrow@users.noreply.github.com>

addons/stock/models/stock_production_lot.py

@@ -17,7 +17,7 @@ class ProductionLot(models.Model):
 
     name = fields.Char(
         'Lot/Serial Number', default=lambda self: self.env['ir.sequence'].next_by_code('stock.lot.serial'),
-        required=True, help="Unique Lot/Serial Number")
+        required=True, help="Unique Lot/Serial Number", index=True)
     ref = fields.Char('Internal Reference', help="Internal reference number in case it differs from the manufacturer's lot/serial number")
     product_id = fields.Many2one(
         'product.product', 'Product', index=True,