Addressing Issue #3205

Fix deprecation warning in Notification.php by handling null values in preg_quote()

Description:
Addressed a deprecation warning in Notification.php related to the preg_quote() function. The warning occurred because preg_quote() was being passed null values, which is deprecated in PHP 8.2.

Changes Made:

• Updated the loop that processes the $vars array to ensure that each element passed to preg_quote() is a string. Added a default value of an empty string ('') when the element is null.

Code Changes:

foreach ($vars as $var) {
    // Ensure $var is a string, default to an empty string if it is null
    $new_vars[] = preg_quote($var ?? '');
}