fix: minimum price variation (#24)

Author: Romazes

QuantConnect.BitfinexBrokerage.ToolBox/BitfinexExchangeInfoDownloader.cs

@@ -141,7 +141,7 @@ public IEnumerable<string> Get()
                 var description = $"{baseLabel}-{quoteLabel}";
                 var contractMultiplier = 1;
                 // default value for minimum_price_variation
-                var minimum_price_variation = "0.00001";
+                var minimum_price_variation = "0.00000001";
                 // default value for lot_size
                 var lot_size = "0.00000001";
                 // follow exchange reference format