[FIX] mail: remove useless hasattr on get_base_url

This check was introduced with d82b897ea1 in 12.0 where `get_base_url` was
not yet a model method.

Since f727cd2645, in saas-12.5, that method is now on model, making the
`hasattr` check useless.

closes odoo/odoo#35057

Signed-off-by: Jérémy Kersten (jke) <jke@openerp.com>

addons/mail/models/mail_thread.py

@@ -2324,7 +2324,7 @@ class MailThread(models.AbstractModel):
             params['token'] = token
 
         link = '%s?%s' % (base_link, url_encode(params))
-        if self and hasattr(self, 'get_base_url'):
+        if self:
             link = self[0].get_base_url() + link
 
         return link