fix previously deprecated table name specification usage in db query builder delete expression

fixes #826

Signed-off-by: binsky <timo@binsky.org>

Author: binsky08

lib/Service/NotificationService.php

@@ -114,8 +114,7 @@ function hasCredentialExpirationNotification($credential): bool {
 
 	function deleteNotificationsOfCredential($credential) {
 		$qb = $this->db->getQueryBuilder();
-		$qb->delete()
-			->from('notifications')
+		$qb->delete('notifications')
 			->where($qb->expr()->eq('object_id', $qb->createNamedParameter($credential->getId(), IQueryBuilder::PARAM_INT)))
 			->andWhere($qb->expr()->eq('object_type', 'credential'));
 		return $qb->execute();