chore: Bump copyright year

Author: levaitamas

LICENSE

@@ -186,7 +186,7 @@
       same "printed page" as the copyright notice for easier
       identification within third-party archives.
 
-   Copyright 2025 l7mp
+   Copyright 2026 l7mp
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.

README.md

@@ -29,7 +29,7 @@ STUNner development is coordinated in Discord, feel free to [join](https://disco
 
 ## License
 
-Copyright 2021-2023 by its authors. Some rights reserved. See [AUTHORS](https://github.com/l7mp/stunner/blob/main/AUTHORS).
+Copyright 2021-2026 by its authors. Some rights reserved. See [AUTHORS](https://github.com/l7mp/stunner/blob/main/AUTHORS).
 
 APACHE License - see [LICENSE](/LICENSE) for full text.