chore(package): update cross-env to version 7.0.0

Closes #38

Author: greenkeeper[bot]

package.json

@@ -96,7 +96,7 @@
     "colors": "^1.1.2",
     "commitizen": "^2.9.6",
     "coveralls": "^3.0.0",
-    "cross-env": "^5.0.1",
+    "cross-env": "^7.0.0",
     "cz-conventional-changelog": "^2.0.0",
     "enzyme": "^3.3.0",
     "enzyme-adapter-react-16": "^1.1.1",