The "Departure Reasons" where hardcoded and couldn't reflect all the valid departure reasons (like "End Of Fixed-Term Contract"). This commit introduces a new model `hr.departure.reason`. closes odoo/odoo#66905 Taskid: 2447056 Related: odoo/enterprise#16709 Related: odoo/upgrade#2211 Signed-off-by: Yannick Tivisse (yti) <yti@odoo.com>