SessionHandler compatibility in PHP 8

[Mark-H]

PHP 8 (not sure which minor exactly) introduced types to the SessionHandler/SessionHandlerInterface which is incompatible with the current implementation of this library.

Deprecated: Return type of PHPSecureSession\SecureHandler::open($save_path, $session_name) should either be compatible with SessionHandler::open(string $path, string $name): bool, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in vendor/ezimuel/php-secure-session/src/SecureHandler.php on line 49
PHP Deprecated:  Return type of PHPSecureSession\SecureHandler::read($id) should either be compatible with SessionHandler::read(string $id): string|false, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in ezimuel/php-secure-session/src/SecureHandler.php on line 60

There is a fork here where @DatabayAG already applied the necessary changes, but it doesn't look like they created a PR.