update copyright year in LICENSE.txt

Signed-off-by: Ceki Gulcu <[email protected]>

Author: ceki

LICENSE.txt

@@ -2,7 +2,7 @@ Logback LICENSE
 ---------------
 
 Logback: the reliable, generic, fast and flexible logging framework.
-Copyright (C) 1999-2015, QOS.ch. All rights reserved.
+Copyright (C) 1999-2024, QOS.ch. All rights reserved.
 
 This program and the accompanying materials are dual-licensed under
 either the terms of the Eclipse Public License v1.0 as published by