[FIX] sale_project: Expecting an ID in write for Many2One

When we are writing on a Many2One field, we are supposed to pass the id
of the object, in this case we are passing directly the object which is
working with the ORM, but is not expected in overrides as the
documentation suppose that an int is passed.

community PR refused in stable:https://github.com/odoo/odoo/pull/88736

closes odoo/odoo#90992

Signed-off-by: Laurent Stukkens (ltu) <ltu@odoo.com>

addons/sale_project/models/sale_order_line.py

@@ -169,7 +169,7 @@ class SaleOrderLine(models.Model):
             # duplicating a project doesn't set the SO on sub-tasks
             project.tasks.filtered('parent_id').write({
                 'sale_line_id': self.id,
-                'sale_order_id': self.order_id,
+                'sale_order_id': self.order_id.id,
             })
         else:
             project_only_sol_count = self.env['sale.order.line'].search_count([