[ISSUE #9976] Update copyright year in NOTICE file to 2026 (#9977)

Author: mxsm

NOTICE

@@ -1,5 +1,5 @@
 Apache RocketMQ
-Copyright 2016-2025 The Apache Software Foundation
+Copyright 2016-2026 The Apache Software Foundation
 
 This product includes software developed at
 The Apache Software Foundation (http://www.apache.org/).