pythonPackages.spacy: fix import error

Importing spacy fails with:

ModuleNotFoundError: No module named 'pkg_resources

spaCy probably worked before because a dependency had setuptools as a
propagated dependency. This change adds setuptools to spacy's
propogatedBuildInputs.

Tested with the en_core_web_sm model.

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

@@ -21,6 +21,7 @@
 , blis
 , wasabi
 , srsly
+, setuptools
 }:
 
 buildPythonPackage rec {
@@ -55,6 +56,7 @@ buildPythonPackage rec {
    blis
    wasabi
    srsly
+   setuptools
   ] ++ lib.optional (pythonOlder "3.4") pathlib;
 
   checkInputs = [