utf8_encode deprecated

utf8_encode is deprecated in PHP8.2 and as I understand it, will be removed in PHP 9. It is used on one line (122) in class-plantuml-renderer-public.php.

A fix would be to replace line 122

$data = utf8_encode( $text );

with

$data = mb_convert_encoding($text, “UTF-8”, mb_detect_encoding($text));