This package is abandoned, I suggest you use symfony/string instead, it provides you with AsciiSlugger
that provides similar functionality via (new AsciiSlugger())->slug('Čokl běžel po džemu');
removes diacritics from strings
$original = 'Čokl běžel po džemu'
$remover = new DiacriticsRemover()
$output = $remover->parse($original);
echo $output; // Cokl bezel po dzemu
via composer: composer require mhlavac/diacritics-remover