List customer groups

{
    "data": [
        {
            "id": 0,
            "created_at": "2019-08-24T14:15:22Z",
            "updated_at": "2019-08-24T14:15:22Z",
            "customers": [
                {
                    "id": 0,
                    "name": "string",
                    "role": "string"
                }
            ]
        }
    ],
    "total": 0
}