webgitgtk 2.12: fix evaluation

Remove reference to unknown maintainer @iyzsong.

pkgs/development/libraries/webkitgtk/2.12.nix

···
     license = licenses.bsd2;
     platforms = platforms.linux;
     hydraPlatforms = [];
-    maintainers = with maintainers; [ iyzsong koral ];
+    maintainers = with maintainers; [ koral ];
   };
 
   preConfigure = "patchShebangs Tools";