Update copyright messages. (#20)

Author: jonathanknowles

LICENSE

@@ -186,7 +186,7 @@
       same "printed page" as the copyright notice for easier
       identification within third-party archives.
 
-   Copyright © 2022 Jonathan Knowles
+   Copyright © 2022–2023 Jonathan Knowles
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.

haskell-example.cabal

@@ -6,7 +6,7 @@ license:        Apache-2.0
 license-file:   LICENSE
 author:         Jonathan Knowles
 maintainer:     mail@jonathanknowles.net
-copyright:      2022 Jonathan Knowles
+copyright:      2022–2023 Jonathan Knowles
 category:       Testing
 synopsis:       Example Haskell Library
 description: