Update readme license year

Author: WyriHaximus

README.md

@@ -8,7 +8,7 @@ This action has only one output, namely `versions`, containing a JSON array with
 
 ## License ##
 
-Copyright 2020 [Cees-Jan Kiewiet](http://wyrihaximus.net/)
+Copyright 2023 [Cees-Jan Kiewiet](http://wyrihaximus.net/)
 
 Permission is hereby granted, free of charge, to any person
 obtaining a copy of this software and associated documentation