How To add image to item with API

I am trying to add image to the item.
i have enabled the image from preference.
i am getting the following response when i try to add image with API

{"code":33003,"message":"Looks like the image is not attached. Please try again"}

my code:

$apiUrl = config('services.zohobooks.api_url');
$url = $apiUrl."items/".$item_id."/image";

$client = new Client();
$headers = [
    "Authorization" =>"Zoho-oauthtoken ".$this->authToken,
];
$query = [
    "organization_id" => $this->organizationId,
];
$image_data = file_get_contents($image_url);
$result = $client->request(
    "POST",
    $url,
    [
        "headers" => $headers,
        "query" => $query,
        "multi_part"=>[
            [
                'name'     => 'image',
                'contents' => $image_data,
                'file-name' => "$item_id.jpg",
            ],
        ],
        'debug' => true,
    ]
);