Bump notice file end year from 2025 to 2026

NOTICE.txt

diff --git a/NOTICE.txt b/NOTICE.txt
index f43b0ff..4e5d97f 100644
--- a/NOTICE.txt
+++ b/NOTICE.txt
@@ -1,5 +1,5 @@
 Apache Commons Testing
-Copyright 2017-2025 The Apache Software Foundation
+Copyright 2017-2026 The Apache Software Foundation
 
 This product includes software developed at
 The Apache Software Foundation (http://www.apache.org/).