docs: update copyright to 2024.

Author: rouilj

doc/conf.py

@@ -72,7 +72,7 @@
 
 # General information about the project.
 project = u'Roundup'
-copyright = u'2009-2021, Richard Jones, Roundup-Team'
+copyright = u'2009-2024, Richard Jones, Roundup-Team'
 
 # The version info for the project you're documenting, acts as replacement for
 # |version| and |release|, also used in various other places throughout the