Kliqqi CMS PHP 8.3 compatability Upgrade and Installation fix

I want to keep using the open-source Kliqqi-CMS (https://github.com/Kliqqi-CMS/Kliqqi-CMS) on a typical shared Linux host that now runs PHP 8.3. The current installer throws compatibility errors and the site breaks as soon as I switch the server to any 8.x build... (Budget: €8 - €30 EUR, Jobs: Apache, cPanel, Linux, MySQL, Open Source, PHP, Plesk, Software Development, Software Testing, Web Development)