The function utf8_decode() was a shortcut to convert strings
encoded in ISO-8859-1 ("Latin 1") to and from UTF-8.
This function was deprecated since PHP 8.2 and will probably
will be removed in future versions:
https://wiki.php.net/rfc/remove_utf8_decode_and_utf8_encode
This change applies the exact proposed equivalent, that is:
mb_convert_encoding($string, 'ISO-8859-1')
Note that this function exists since PHP 4, so, there are no
compatibility issues.
https://we.phorge.it/T15188
https://wiki.php.net/rfc/remove_utf8_decode_and_utf8_encode
https://www.php.net/manual/en/function.utf8-decode
https://www.php.net/manual/en/function.mb-convert-encoding.php
https://github.com/rectorphp/rector/blob/main/docs/rector_rules_overview.md#utf8decodeencodetombconvertencodingrector