Add 8.4 support

[littlejohn-ai]

PHP Deprecated:  OpenAI::client(): Implicitly marking parameter $organization as nullable is deprecated, the explicit nullable type must be used instead in vendor/openai-php/client/src/OpenAI.php on line 13

Deprecated: OpenAI::client(): Implicitly marking parameter $organization as nullable is deprecated, the explicit nullable type must be used instead in vendor/openai-php/client/src/OpenAI.php on line 13

It's easy fix:

public static function client(string $apiKey, ?string $organization = null): Client

Thank you

[gehrisandro]

Make sure you are using the latest release.