chore: update copyright to OpenFeature Maintainers (#195)

Signed-off-by: Jonathan Norris <[email protected]>

Author: jonathannorris

LICENSE

@@ -186,7 +186,7 @@
       same "printed page" as the copyright notice for easier
       identification within third-party archives.
 
-   Copyright [yyyy] [name of copyright owner]
+   Copyright OpenFeature Maintainers
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.