Update Copyright (#419)

Author: crunchymaggie

LICENSE.txt

@@ -4,7 +4,7 @@ LICENSE AND COPYRIGHT
 PG Partition Manager (pg_partman) is released under the PostgreSQL License, a liberal Open Source license, similar to the BSD or MIT licenses.
 
 Copyright (c) 2017 OmniTI, Inc.
-Copyright (c) 2018-2021 Crunchy Data Solutions, Inc.
+Copyright (c) 2018-2022 Crunchy Data Solutions, Inc.
 
 Permission to use, copy, modify, and distribute this software and its documentation for any purpose, without fee, and without a written agreement is hereby granted, provided that the above copyright notice and this paragraph and the following two paragraphs appear in all copies.