Update all 2011 dates to 2021.
diff --git a/upb/json_encode.c b/upb/json_encode.c
index 03642a8..bc31baf 100644
--- a/upb/json_encode.c
+++ b/upb/json_encode.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2009-2011, Google LLC
+ * Copyright (c) 2009-2021, Google LLC
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without