buildPython*: remove pythonRecompileBytecodeHook as dependency

This hook was added to get reproducible bytecode. Because it was causing
issues it was disabled, but still kept as a dependency. Now the main
issue with bytecode reproducibility has been resolved by updating pip to
20.2.4, we remove this hook as a dependency.

If a package with Python code is not yet reproducible, one could add
this hook to `nativeBuildInputs`.

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

@@ -41,8 +41,4 @@ buildPythonPackage (rec {
       any platform that supports the standard Python pty module.
     '';
   };
-# TODO: move into main set, this was to avoid a rebuild
-} // lib.optionalAttrs (!isPy3k ) {
-  # syntax error in _async module, likely intended only for Python 3.
-  dontUsePythonRecompileBytecode = !isPy3k;
 })