curl --request GET \
  --url https://api.affonso.io/v1/coupons/{id} \
  --header 'Authorization: Bearer <token>'

{
  "success": true,
  "data": {
    "id": "<string>",
    "affiliate_id": "<string>",
    "program_id": "<string>",
    "code": "<string>",
    "discount_type": "percentage",
    "discount_value": 123,
    "duration": "forever",
    "duration_in_months": 123,
    "product_ids": [
      "<string>"
    ],
    "provider": "stripe",
    "provider_coupon_id": "<string>",
    "provider_promo_code_id": "<string>",
    "created_at": "2023-11-07T05:31:56Z",
    "updated_at": "2023-11-07T05:31:56Z"
  }
}