Use string instead of float64 in CreateOrderService

[taobig]

• binance-connector-go/account.go

  Line 184 in fc4f372

  type CreateOrderService struct {

• https://developers.binance.com/docs/binance-spot-api-docs/rest-api/trading-endpoints#new-order-trade

[YakutovDmitriy]

+1

I could be really helpful. Right now I keep receiving responses like Parameter 'quantity' has too much precision., because I can't control the serialization of Quantity field