Fix error when adding custom port to mysql host - #2236

2024/10/01 11:07:24 [error] 298#298: *1 FastCGI sent in stderr: "PHP message: PHP Fatal error:  Uncaught TypeError: mysqli::__construct(): Argument #5 ($port) must be of type ?int, string given in /app/www/public/include/dblayer/functions_mysqli.inc.php:52
Stack trace:
#0 /app/www/public/include/dblayer/functions_mysqli.inc.php(52): mysqli->__construct()
#1 /app/www/public/admin/include/functions_install.inc.php(103): pwg_db_connect()
#2 /app/www/public/install.php(260): install_db_connect()
#3 {main}
  thrown in /app/www/public/include/dblayer/functions_mysqli.inc.php on line 52"