chore(package): update mocha to version 6.1.1

Closes #19

Author: greenkeeper[bot]

package.json

@@ -15,7 +15,7 @@
     "native-css": "^2.0.0",
     "path": "^0.12.7",
     "loader-utils": "^1.1.0",
-    "mocha": "^5.0.3",
+    "mocha": "^6.1.1",
     "should": "^7.1.1"
   },
   "scripts": {