Update copyright to 2021
diff --git a/functions.sh b/functions.sh
index 96afb05..f117ad7 100755
--- a/functions.sh
+++ b/functions.sh
@@ -2,7 +2,7 @@
 #
 # SPDX-License-Identifier: BSD-2-Clause
 #
-# Copyright (c) 2018-2020 Gavin D. Howard and contributors.
+# Copyright (c) 2018-2021 Gavin D. Howard and contributors.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are met: