Fix case sensitivity of email when saving settings

Otherwise we detect a email change all the time and since email are
immutable in ldap this prevent updating other fields.

Related: #33813

Signed-off-by: Carl Schwan <carl@carlschwan.eu>

apps/settings/lib/Controller/UsersController.php

@@ -484,7 +484,7 @@ protected function saveUserSettings(IAccount $userAccount): void {
 
  $oldEmailAddress = $userAccount->getUser()->getSystemEMailAddress();
  $oldEmailAddress = strtolower((string)$oldEmailAddress);
- if ($oldEmailAddress !== $userAccount->getProperty(IAccountManager::PROPERTY_EMAIL)->getValue()) {
+ if ($oldEmailAddress !== strtolower($userAccount->getProperty(IAccountManager::PROPERTY_EMAIL)->getValue())) {
  // this is the only permission a backend provides and is also used
  // for the permission of setting a email address
  if (!$userAccount->getUser()->canChangeDisplayName()) {