Updating Expat copyright year according to the Expat's COPYING file

Though it's still outdated (2022)

(cherry picked from commit 836f8953d43ec785d50d0296db260076c41f7917)

Source commit: 4a71185591d9f9a369945ec11de7d09a6846391a

source/resource/LicenseExpat.txt

@@ -1,6 +1,6 @@
 Expat
 Copyright (c) 1998-2000 Thai Open Source Software Center Ltd and Clark Cooper
-Copyright (c) 2001-2017 Expat maintainers
+Copyright (c) 2001-2022 Expat maintainers
 
 Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: