Convert &#... to UTF-8 representatives

convert_to_utf8.pl

use Encode qw/encode decode/;
use HTML::Entities;

my $string = "Darf Kategorisierung verändern?";
$string = decode("big5", $string);  # big5 to internal utf8 -> utf8::is_utf8($string) is true
decode_entities($string);           # decode HTML entities
$string = encode('utf8', $string);  # internal utf8 to raw bytes, utf8::is_utf8($string) is false
say $string;                        # Darf Kategorisierung verändern?