Change the years range in LICENSE (#97)

Author: zhelenskiy

LICENSE

@@ -186,7 +186,7 @@ Apache License
       same "printed page" as the copyright notice for easier
       identification within third-party archives.
 
-   Copyright 2000-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+   Copyright 2000-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.