Fix Python 3 support for pythonPackages.ncclient (#68226)

pkgs/development/python-modules/lxml/default.nix

···
   };
 
   nativeBuildInputs = [ libxml2.dev libxslt.dev ];
-  buildInputs = [ libxml2 libxslt ];
+  propagatedBuildInputs = [ libxml2 libxslt ];
 
   hardeningDisable = stdenv.lib.optional stdenv.isDarwin "format";
 

pkgs/development/python-modules/ncclient/default.nix

···
 , paramiko
 , selectors2
 , lxml
-, libxml2
-, libxslt
 , nose
 , rednose
 }:
···
   checkInputs = [ nose rednose ];
 
   propagatedBuildInputs = [
-    paramiko lxml libxml2 libxslt selectors2
+    paramiko lxml selectors2
   ];
 
   checkPhase = ''