Official support for php8.4

## Is your feature request related to a problem? Please describe.

Add official support for PHP8.4

## Describe the solution you'd like

assert PHP 8.4 support in CI unit tests and such.


## Additional context

PHP 8.4 is not released, yet. release is planned for Nov 21 2024.
see <https://wiki.php.net/todo/php84>