chore(package): update webpack-cli to version 3.0.8

Closes #39

Author: greenkeeper[bot]

package.json

@@ -84,7 +84,7 @@
     "nyc": "^12.0.1",
     "request-promise": "^4.2.2",
     "webpack": "^4.2.0",
-    "webpack-cli": "^2.0.13",
+    "webpack-cli": "^3.0.8",
     "yargs": "^11.1.0"
   }
 }