GitHub API WebHooks returning 404 (unauthorized)

Hi everybody!

My users connect to GitHub with socialite and one thing I (want to) use that for is setting up a web hook for push events on repositories.

I'm asking for the scope (and getting it): GithubLoginController.php

    public function redirectToProvider()
    {
        return Socialite::driver('github')
                        ->scopes(['repo', 'admin:repo_hook'])
                        ->redirect();
    }

Then try to set up the hook:

GitHubClient.php

use GuzzleHttp\Client;
use Illuminate\Support\Facades\Auth;

class GithubClient
{
    protected $client   = null;
    protected $endpoint = 'https://api.github.com';

    public function __construct()
    {
        $this->client = new Client([
            'base_uri' => $this->endpoint,
            'headers'  => [
                'Authorization' => auth()->user()->github()->acces_token,
            ],
        ]);
    }

    public function post($path, $payload)
    {
        $ret = $this->client->post($path, [
            'json' => $payload,
        ]);
        return json_decode($ret->getBody());
    }


    public function createWebhook($username, $updateable)
    {
        $payload = [
            'name' => 'web',
            'config' => [
                'url' => route('webhooks.github.payload', ['updateable' => $updateable]),
                'content_type' => 'json',
            ],
        ];

        return $this->post("/repos/{$username}/{$updateable->repository}/hooks", $payload);
    }

But I get this error: Client error: POST https://api.github.com/repos/melker-io/test/hooks resulted in a 404 Not Found response: { "message": "Not Found", "documentation_url": "https://developer.github.com/v3/repos/hooks/#create-a-hook" }

On GitHub a 404 like this means unauthorized - but I think I've got the correct scope? I've tried a few different scopes (write:repo_hook) but can't get it to work.

Anyone know what I'm doing wrong?