[FIX] mail: res.users.settings have no display_name

Before this commit res.users.settings have no display_name.

closes odoo/odoo#135106

Signed-off-by: Sébastien Theys (seb) <seb@odoo.com>

addons/mail/models/res_users_settings.py

@@ -7,6 +7,7 @@ from odoo import api, fields, models
 class ResUsersSettings(models.Model):
     _name = 'res.users.settings'
     _description = 'User Settings'
+    _rec_name = 'user_id'
 
     user_id = fields.Many2one('res.users', string="User", required=True, readonly=True, ondelete='cascade')
     is_discuss_sidebar_category_channel_open = fields.Boolean(string="Is discuss sidebar category channel open?", default=True)