plistutil: Update copyright header
diff --git a/tools/plistutil.c b/tools/plistutil.c
index 736e3e7..bbce7c7 100644
--- a/tools/plistutil.c
+++ b/tools/plistutil.c
@@ -2,8 +2,9 @@
  * plistutil.c
  * Simple tool to convert a plist into different formats
  *
- * Copyright (c) 2009-2015 Martin Szulecki All Rights Reserved.
- * Copyright (c) 2008 Zach C. All Rights Reserved.
+ * Copyright (c) 2009-2020 Martin Szulecki All Rights Reserved.
+ * Copyright (c) 2013-2020 Nikias Bassen, All Rights Reserved.
+ * Copyright (c) 2008 Zach C., All Rights Reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public