revert unnecessary changes

Author: Manabu-GT

README.md

@@ -296,7 +296,7 @@ Thanks for reading!
 License
 ----------
 
-    Copyright 2025 Manabu-GT
+    Copyright 2017–2025 Manabu-GT
 
     Licensed under the Apache License, Version 2.0 (the "License");
     you may not use this file except in compliance with the License.