Update Item Quantity

curl --request PUT \
  --url https://api.firmly.work/api/v1/domains/staging.luma.gift/cart/line-items/WS12-XS-Orange \
  --header 'x-firmly-authorization: YOUR_TOKEN' \
  --header 'Content-Type: application/json' \
  --data '{"quantity": 2}'

{
  "cart_id": "1e43868c-d4a5-418c-bd6b-5fff043550d2",
  "platform_id": "example",
  "shop_id": "staging.luma.gift",
  "display_name": "Luma Store",
  "line_items": [
    {
      "line_item_id": "1ee530e1-063d-4e07-afb2-e7e65245977e",
      "platform_line_item_id": "4df9941b-bd06-4495-8759-61c6145dc408",
      "sku": "WS12-XS-Orange",
      "base_sku": "WS12",
      "quantity": 2,
      "description": "Radiant Tee - Orange XS",
      "price": {
        "currency": "USD",
        "value": 22.00,
        "symbol": "$",
        "number": 2200
      },
      "line_price": {
        "currency": "USD",
        "value": 44.00,
        "symbol": "$",
        "number": 4400
      },
      "msrp": {
        "currency": "USD",
        "value": 22.00,
        "symbol": "$",
        "number": 2200
      },
      "image": {
        "url": "https://cdn.staging.luma.gift/products/radiant-tee/orange.jpg"
      },
      "requires_shipping": true
    }
  ],
  "sub_total": {
    "currency": "USD",
    "value": 1739.98,
    "symbol": "$",
    "number": 173998
  },
  "shipping_total": {
    "currency": "USD",
    "value": 0,
    "symbol": "$",
    "number": 0
  },
  "tax": {
    "currency": "USD",
    "value": 4.40,
    "symbol": "$",
    "number": 440
  },
  "total": {
    "currency": "USD",
    "value": 48.40,
    "symbol": "$",
    "number": 4840
  },
  "payment_method_options": [
    {
      "type": "CreditCard",
      "wallet": "user"
    }
  ]
}