[FIX] calendar: readonly attribute expects boolean
[FIX] calendar: readonly attribute expects boolean

Followup on https://github.com/odoo/odoo/commit/6bc14c9142baedd98d8833c7cf77d1ee174e3f7f

closes odoo/odoo#33155

Signed-off-by: Thibault Delavallee (tde) <2d325771bb6e8870d87f0f3f7b45589a8338e550@openerp.com>
ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo