chore(package): update cross-env to version 3.2.4

https://greenkeeper.io/

Author: greenkeeper[bot]

package.json

@@ -44,7 +44,7 @@
     "codecov": "^1.0.1",
     "coveralls": "^2.11.16",
     "cpy-cli": "^1.0.1",
-    "cross-env": "^3.2.3",
+    "cross-env": "^3.2.4",
     "css-modules-require-hook": "^4.0.5",
     "enzyme": "^2.7.1",
     "eslint": "^3.16.0",