Update year

Dotnet/JsonFileSerializer.cs

@@ -1,9 +1,3 @@
-// Copyright(c) 2019-2025 pypy, Natsumi and individual contributors.
-// All rights reserved.
-//
-// This work is licensed under the terms of the MIT license.
-// For a copy, see <https://opensource.org/licenses/MIT>.
-
 using Newtonsoft.Json;
 using System.IO;
 using System.Text;