Tweak copyright years for less maintenance

Author: Lars-Magnus Skog

README.md

@@ -47,7 +47,7 @@ Error encoding data.
 
 ## License
 
-Copyright © 2012-2018 `level-errors` contributors.
+Copyright © 2012-present `level-errors` contributors.
 
 `level-errors` is licensed under the MIT license. All rights not explicitly granted in the MIT license are reserved. See the included `LICENSE.md` file for more details.