treewide: remove the-kenny from maintainers

@the-kenny did a good job in the past and is set as maintainer in many package,
however since 2017-2018 he stopped contributing. To create less confusion
in pull requests when people try to request his feedback, I removed him as
maintainer from all packages.

pkgs/tools/backup/btrbk/default.nix

@@ -46,7 +46,7 @@ stdenv.mkDerivation rec {
     homepage = "https://digint.ch/btrbk";
     license = licenses.gpl3;
     platforms = platforms.unix;
-    maintainers = with maintainers; [ asymmetric the-kenny ];
+    maintainers = with maintainers; [ asymmetric ];
     inherit version;
   };
 }

pkgs/tools/backup/httrack/default.nix

@@ -17,7 +17,6 @@ stdenv.mkDerivation rec {
     description = "Easy-to-use offline browser / website mirroring utility";
     homepage    = "http://www.httrack.com";
     license     = licenses.gpl3;
-    maintainers = with maintainers; [ the-kenny ];
     platforms   = with platforms; unix;
   };
 }

pkgs/tools/backup/rdiff-backup/default.nix

@@ -19,6 +19,5 @@ python2Packages.buildPythonApplication {
     homepage = "http://rdiff-backup.nongnu.org/";
     license = stdenv.lib.licenses.gpl2;
     platforms = stdenv.lib.platforms.all;
-    maintainers = with stdenv.lib.maintainers; [ the-kenny ];
   };
 }