Update COPYING
Copyright year should be 2019 for 2.2.9?
Copyright (c) 1998-2000 Thai Open Source Software Center Ltd and Clark Cooper
-Copyright (c) 2001-2017 Expat maintainers
+Copyright (c) 2001-2019 Expat maintainers
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
