shotgun: add novenary to maintainers

I am upstream, so I think it's appropriate for me to be listed here too.

pkgs/tools/graphics/shotgun/default.nix

···
     description = "Minimal X screenshot utility";
     homepage = "https://github.com/neXromancers/shotgun";
     license = with licenses; [ mpl20 ];
-    maintainers = with maintainers; [ figsoda lumi ];
+    maintainers = with maintainers; [ figsoda lumi novenary ];
     platforms = platforms.linux;
   };
 }