Update year of Copyright

Author: yasulab

README.md

@@ -134,7 +134,7 @@ So, this application can be used and modified under the MIT License! 🆗
 
 ### The MIT License (MIT)
 
-Copyright © 2012-2019 [CoderDojo Japan Association](https://coderdojo.jp/)
+Copyright © 2012-2020 [CoderDojo Japan Association](https://coderdojo.jp/)
 
 Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: