Add php 8.4 to the list of runtimes

[jobvink]

With PHP 8.4's release around the corner, developers might want to start testing it. I added PHP 8.4 to the list of runtimes.

While creating this pull request, I discovered two issues:

• The imagick PHP extension cannot load due to a removed function. (a fix is currently being developed, Fix removed "php_strtolower" for PHP 8.4 Imagick/imagick#690)
• The Swoole extension for PHP 8.4 still needs to be released. (so I commented this out in the Dockerfile)

[Jubeki]

Can you add PHP 8.4 to the Docker Compose Tests Matrix?

[taylorotwell]

Thanks!