fix: handle x-request-id in MetaInformation

[olegnowikow]

What:

• Bug Fix
• New Feature

Description:

Fix handle of the x-request-id header when using models that do not return it:

<?php

namespace App\Service;

use OpenAI;

final class Ai
{
    private $client;

    public function __construct()
    {
        $this->client = OpenAI::factory()
            ->withBaseUri('http://localhost:8888/v1')
            ->make();
    }

    public function getModels()
    {
        return $this->client->models()->list();
    }
}

Related:

#253

[gehrisandro]

Thans @olegnowikow for your PR!