Bump copyright year

Author: acogoluegnes

src/main/java/com/rabbitmq/client/impl/AMQConnection.java

@@ -34,7 +34,7 @@
 import java.util.concurrent.atomic.AtomicBoolean;
 
 final class Copyright {
- final static String COPYRIGHT="Copyright (c) 2007-2020 VMware, Inc. or its affiliates.";
+ final static String COPYRIGHT="Copyright (c) 2007-2021 VMware, Inc. or its affiliates.";
  final static String LICENSE="Licensed under the MPL. See https://www.rabbitmq.com/";
 }