mwic: Fix Python wrapping

Fixes this error when mwic is installed with nix-env:

$ mwic
Traceback (most recent call last):
  File "/home/anders/.nix-profile/bin/mwic", line 30, in <module>
    import lib.cli  # pylint: disable=wrong-import-position
  File "/nix/store/zn9jli2v7znh6w6rpkjp6w0iz3na79yz-mwic-0.7.8/share/mwic/lib/cli.py", line 32, in <module>
    import enchant.tokenize
ModuleNotFoundError: No module named 'enchant'

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

pkgs/applications/misc/mwic/default.nix

@@ -18,7 +18,7 @@ stdenv.mkDerivation rec {
   propagatedBuildInputs = with pythonPackages; [ pyenchant regex ];
 
   postFixup = ''
-    buildPythonPath "$out"
+    wrapPythonPrograms
   '';
 
   meta = with stdenv.lib; {