docs: Update copyright for 2026
diff --git a/COPYING b/COPYING
index 3f9ab862..a59751f9 100644
--- a/COPYING
+++ b/COPYING
@@ -1,4 +1,4 @@
-Copyright (C) 2019-2025 Mintsuki and contributors.
+Copyright (C) 2019-2026 Mintsuki and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
