Update the copyright year in README.md

Author: ekwankyu

README.md

@@ -679,7 +679,7 @@ information, patches, and build scripts are in the accompanying
 part of the Sage git repository.
 
 <p align="center">
-   Copyright (C) 2005-2024 The Sage Development Team
+   Copyright (C) 2005-2025 The Sage Development Team
 </p>
 <p align="center">
    https://www.sagemath.org