Cleaned out an unused testing variable.

Author: davemx

src/main/java/com/binance/api/client/config/BinanceApiConfig.java

@@ -10,11 +10,6 @@ public class BinanceApiConfig {
 	 */
 	private static String BASE_DOMAIN = "binance.com";
 
-	/**
-	 * Default receiving window.
-	 */
-	private static long DEFAULT_RECEIVING_WINDOW = 6_000_000L;
-
 	/**
 	 * Set the URL base domain name (e.g., binance.com).
 	 *