python310Packages.schema: don't depend on contextlib2

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

···
 { lib
 , buildPythonPackage
-, contextlib2
 , fetchPypi
 , mock
 , pytestCheckHook
 , pythonOlder
+, pythonRelaxDepsHook
 }:
 
 buildPythonPackage rec {
···
     hash = "sha256-8GcXESxhiVyrxHB3UriHFuhCCogZ1xQEUB4RT5EEMZc=";
   };
 
-  propagatedBuildInputs = [
-    contextlib2
+  nativeBuildInputs = [
+    pythonRelaxDepsHook
+  ];
+
+  pythonRemoveDeps = [
+    "contextlib2"
   ];
 
   nativeCheckInputs = [