chore(package): update chai to version 4.1.2

Closes #13

Author: greenkeeper[bot]

package.json

@@ -33,7 +33,7 @@
     "babel-loader": "^7.0.0",
     "babel-preset-env": "^1.3.3",
     "babel-register": "^6.24.1",
-    "chai": "3.5.0",
+    "chai": "4.1.2",
     "chalk": "1.1.3",
     "cheerio": "0.22.0",
     "compression": "1.6.2",