treewide: purge maintainers.urkud

It's sad, but he's been inactive for the last five years.
Keeping such people in meta.maintainers is counter-productive.

pkgs/tools/text/catdoc/default.nix

@@ -15,6 +15,6 @@ stdenv.mkDerivation rec {
     description = "MS-Word/Excel/PowerPoint to text converter";
     platforms = platforms.all;
     license = licenses.gpl2;
-    maintainers = with maintainers; [ urkud ndowens ];
+    maintainers = with maintainers; [ ndowens ];
   };
 }

pkgs/tools/text/ebook-tools/default.nix

@@ -18,7 +18,7 @@ stdenv.mkDerivation rec {
   meta = {
     homepage = "http://ebook-tools.sourceforge.net";
     description = "Tools and library for dealing with various ebook file formats";
-    maintainers = [ stdenv.lib.maintainers.urkud ];
+    maintainers = [ ];
     platforms = stdenv.lib.platforms.all;
   };
 }

pkgs/tools/text/kdiff3/default.nix

@@ -30,7 +30,7 @@ let
       homepage = http://kdiff3.sourceforge.net/;
       license = licenses.gpl2Plus;
       description = "Compares and merges 2 or 3 files or directories";
-      maintainers = with maintainers; [ viric urkud peterhoeg ];
+      maintainers = with maintainers; [ viric peterhoeg ];
       platforms = with platforms; linux;
     };
   };

pkgs/tools/text/odt2txt/default.nix

@@ -19,6 +19,6 @@ stdenv.mkDerivation rec {
     homepage = http://stosberg.net/odt2txt;
     platforms = stdenv.lib.platforms.all;
     lincense = stdenv.lib.licenses.gpl2;
-    maintainers = [ stdenv.lib.maintainers.urkud ];
+    maintainers = [ ];
   };
 }