Type hint mixed.

Hi,
I am using your package (version 3.1.3) which should be able to run on php 7.4 according to your docs and composer.json php: >=7.4.0.

However in the file Tool.php you are using mixed type hint, which was introduced in PHP 8.0 (https://php.watch/versions/8.0/mixed-type)

zasilkovna/src/Tool.php

Line 14 in 8846427

public static function convertToString(mixed $input): string

Is this a bug or feature? 🙃

Same problem here, running it on PHP 7.4 raises this problem.
Argument 1 passed to Salamek\Zasilkovna\Tool::convertToString must be an instance of Salamek\Zasilkovna\mixed, null given

Ok ok!, i have removed that in 3.1.4, but the second Debian 12 is released as stable, i'm flooding this project with PHP 8.1 stuff lol

Wow. Thank you for such a prompt fix 🙏

Thanks