Update copyright notices to 2023

debian/copyright

@@ -11,7 +11,7 @@ Files:
  debian/*
 Copyright:
  2013 Praveen Arimbrathodiyil <praveen@debian.org>
- 2017-2022 Christoph Biedl <debian.axhn@manchmal.in-ulm.de>
+ 2017-2023 Christoph Biedl <debian.axhn@manchmal.in-ulm.de>
 License: Expat
 
 License: Expat-nginx