Fix copyright year in reenable_warnings.h

Change-Id: Idf38790fb80c78e0e4cc28e4272b99fc7be1f123

include/ceres/internal/reenable_warnings.h

diff --git a/include/ceres/internal/reenable_warnings.h b/include/ceres/internal/reenable_warnings.h
index 5e6114f..d2db397 100644
--- a/include/ceres/internal/reenable_warnings.h
+++ b/include/ceres/internal/reenable_warnings.h
@@ -1,5 +1,5 @@
 // Ceres Solver - A fast non-linear least squares minimizer
-// Copyright 2025 Google Inc. All rights reserved.
+// Copyright 2026 Google Inc. All rights reserved.
 // http://ceres-solver.org/
 //
 // Redistribution and use in source and binary forms, with or without