[FIX] product: sequence on product vendor list
[FIX] product: sequence on product vendor list

The sequence on product supplier info (vendor list) has the handle
widget to be adjusted but was readonly.

task-2123442

closes odoo/odoo#40552

X-original-commit: 79c439470084fa960360228ebe53e8ff13cf4ff5
Signed-off-by: Simon Lejeune (sle) <1969d8dff896674c2d819e813f5e88ca826229ab@openerp.com>

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo