Update copyrights to 2020.
diff --git a/src/dns-protocol.h b/src/dns-protocol.h
index 523763c..8edb9f3 100644
--- a/src/dns-protocol.h
+++ b/src/dns-protocol.h
@@ -1,4 +1,4 @@
-/* dnsmasq is Copyright (c) 2000-2018 Simon Kelley
+/* dnsmasq is Copyright (c) 2000-2020 Simon Kelley
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by