curl --request PATCH \
  --url https://api.hemenmagaza.com/v1/cart/{cart_token}/items/{item_id} \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "quantity": 2
}'

{
  "cart_token": "<string>",
  "items": [
    {
      "id": 123,
      "product_id": 123,
      "name": "<string>",
      "quantity": 123,
      "unit_price": 123,
      "total": 123,
      "sku": "<string>",
      "options": {}
    }
  ],
  "totals": {
    "subtotal": 123,
    "tax": 123,
    "shipping": 123,
    "discount": 123,
    "grand_total": 123
  },
  "currency": "<string>"
}