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

Closes #133

Author: greenkeeper[bot]

package.json

@@ -27,7 +27,7 @@
   },
   "devDependencies": {
     "concurrently": "4.0.1",
-    "cross-env": "^5.2.0",
+    "cross-env": "^7.0.0",
     "esdoc": "1.1.0",
     "esdoc-standard-plugin": "1.0.0",
     "eslint": "5.7.0",