Update LICENSE with copyright year (#15727)

Author: sobolevn

LICENSE

@@ -4,8 +4,8 @@ Mypy (and mypyc) are licensed under the terms of the MIT license, reproduced bel
 
 The MIT License
 
-Copyright (c) 2012-2022 Jukka Lehtosalo and contributors
-Copyright (c) 2015-2022 Dropbox, Inc.
+Copyright (c) 2012-2023 Jukka Lehtosalo and contributors
+Copyright (c) 2015-2023 Dropbox, Inc.
 
 Permission is hereby granted, free of charge, to any person obtaining a
 copy of this software and associated documentation files (the "Software"),