Update of copyright year to 2021

COPYING

@@ -1,6 +1,6 @@
-Copyright (c) 2016-2020 The Zcash developers
-Copyright (c) 2009-2020 The Bitcoin Core developers
-Copyright (c) 2009-2020 Bitcoin Developers
+Copyright (c) 2016-2021 The Zcash developers
+Copyright (c) 2009-2021 The Bitcoin Core developers
+Copyright (c) 2009-2021 Bitcoin Developers
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

contrib/debian/copyright

@@ -4,9 +4,9 @@ Upstream-Contact: Electric Coin Company <team@electriccoin.co>
 Source: https://github.com/zcash/zcash
 
 Files: *
-Copyright: 2016-2020, The Zcash developers
- 2009-2020, Bitcoin Core developers
- 2009-2020, Bitcoin Developers
+Copyright: 2016-2021, The Zcash developers
+ 2009-2021, Bitcoin Core developers
+ 2009-2021, Bitcoin Developers
 License: Expat
 Comment: The Bitcoin Core developers encompasses the current developers listed on
  bitcoin.org, as well as the numerous contributors to the project.