Update cross-env to the latest version 🚀 (#905)

* chore(package): update cross-env to version 5.2.1

* chore(package): update lockfile package-lock.json

Author: greenkeeper[bot]

package-lock.json

@@ -52,7 +52,7 @@
     "browserify": "16.5.0",
     "codecov": "3.5.0",
     "core-js": "3.2.1",
-    "cross-env": "5.2.0",
+    "cross-env": "5.2.1",
     "eslint": "6.3.0",
     "eslint-plugin-flowtype": "4.0.0",
     "express": "4.17.1",