E_DEPRECATED messages when running against PHP 8.4

[campbell-m]

When running against the alpha releases of PHP 8.4 a number of E_DEPRECATED messages are generated. For example,

E_DEPRECATED in C:\inetpub\wwwroot\xxxx\lib\CAS.php at line 348
phpCAS::client(): Implicitly marking parameter $sessionHandler as nullable is deprecated, the explicit nullable type must be used instead