[FIX] event: Allow to override default method

Without this patch, you have to redefine the field to be able to override this field.

closes odoo/odoo#33049

Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>

addons/event/models/event.py

@@ -70,7 +70,7 @@ class EventType(models.Model):
     event_type_mail_ids = fields.One2many(
         'event.type.mail', 'event_type_id', string='Mail Schedule',
         copy=False,
-        default=_get_default_event_type_mail_ids)
+        default=lambda self: self._get_default_event_type_mail_ids())
 
     @api.onchange('has_seats_limitation')
     def _onchange_has_seats_limitation(self):