pythonPackages.tzdata: run tests

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

···
-{ lib, buildPythonPackage, fetchPypi }:
+{ lib
+, buildPythonPackage
+, fetchPypi
+, pythonOlder
+, pytestCheckHook
+, pytest-subtests
+, importlib-resources
+}:
 
 buildPythonPackage rec {
   pname = "tzdata";
···
     inherit pname version;
     sha256 = "sha256-4ZxzUfiHUioaxznSEEHlkt3ebdG3ZP3vqPeys1UdPTg=";
   };
+
+  checkInputs = [
+    pytestCheckHook
+    pytest-subtests
+  ] ++ lib.optional (pythonOlder "3.7") importlib-resources;
 
   pythonImportsCheck = [ "tzdata" ];