Bump copyright dates.
diff --git a/lib/zip_file_set_encryption.c b/lib/zip_file_set_encryption.c
index b0cbe5c..7e7a9b1 100644
--- a/lib/zip_file_set_encryption.c
+++ b/lib/zip_file_set_encryption.c
@@ -1,6 +1,6 @@
 /*
   zip_file_set_encryption.c -- set encryption for file in archive
-  Copyright (C) 2016-2017 Dieter Baron and Thomas Klausner
+  Copyright (C) 2016-2018 Dieter Baron and Thomas Klausner
 
   This file is part of libzip, a library to manipulate ZIP archives.
   The authors can be contacted at <libzip@nih.at>