[FIX] mail: prevent traceback when updating volumes

Before this commit, the server was returning the wrong format
for the partner data.

This commit fixes this issue.

closes odoo/odoo#79871

X-original-commit: bf2db96093e955eebb23777c153c6583352cc0e9
Signed-off-by: Sébastien Theys (seb) <seb@odoo.com>

addons/mail/models/res_users_settings_volumes.py

@@ -30,7 +30,7 @@ class ResUsersSettingsVolumes(models.Model):
                 'id': volume_setting.guest_id.id,
                 'name': volume_setting.guest_id.name,
             })] if volume_setting.guest_id else [('clear',)],
-            'partner_id': [('insert-and-replace', {
+            'partner': [('insert-and-replace', {
                 'id': volume_setting.partner_id.id,
                 'name': volume_setting.partner_id.name,
             })] if volume_setting.partner_id else [('clear',)]