`LdapUserBackend`: Import exception `QueryException`

Method `LdapUserBackend::requireQueryColumn()` throws exception `QueryException`

library/Icinga/Authentication/User/LdapUserBackend.php

@@ -9,6 +9,7 @@ use Icinga\Data\Inspectable;
 use Icinga\Data\Inspection;
 use Icinga\Exception\AuthenticationException;
 use Icinga\Exception\ProgrammingError;
+use Icinga\Exception\QueryException;
 use Icinga\Repository\LdapRepository;
 use Icinga\Repository\RepositoryQuery;
 use Icinga\Protocol\Ldap\LdapException;