treewide: remove unused with statements from maintainer lists

$ find -type f -name '*.nix' -print0 | xargs -P "$(nproc)" -0 sed -i \
  -e 's!with lib.maintainers; \[ *\];![ ];!' \
  -e 's!with maintainers; \[ *\];![ ];!'

pkgs/development/python2-modules/pygobject/default.nix

@@ -43,6 +43,6 @@ buildPythonPackage rec {
     homepage = "https://pygobject.readthedocs.io/";
     description = "Python bindings for GLib";
     license = licenses.gpl2;
-    maintainers = with maintainers; [ ];
+    maintainers = [ ];
   };
 }