Update copyright year

mmistakes · mmistakes · commit a26f3d2b36d6 · 2021-07-05T21:11:46.000-04:00
diff --git a/LICENSE b/LICENSE
@@ -1,6 +1,6 @@
 The MIT License (MIT)
 
-Copyright (c) 2017-2018 Michael Rose and contributors
+Copyright (c) 2017-2021 Michael Rose and contributors
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
