Update copyright dates in LICENSE-APACHE

Author: TimmFitschen

LICENSE-APACHE

@@ -186,7 +186,7 @@ APPENDIX: How to apply the Apache License to your work.
    same "printed page" as the copyright notice for easier
    identification within third-party archives.
 
-Copyright 2014-2020 The Rust Project Developers
+Copyright 2017-2021 The Rust Project Developers
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.