update copyright year

Author: Cristy

LICENSE

@@ -38,7 +38,7 @@ Terms and Conditions for Use, Reproduction, and Distribution
 
 The legally binding and authoritative terms and conditions for use, reproduction, and distribution of ImageMagick follow:
 
-Copyright 1999-2021 ImageMagick Studio LLC, a non-profit organization dedicated to making software imaging solutions freely available.
+Copyright @ 1999 ImageMagick Studio LLC, a non-profit organization dedicated to making software imaging solutions freely available.
 
 1. Definitions.