chore(package): update webpack-cli to version 3.1.2

Closes #20

Author: greenkeeper[bot]

package.json

@@ -32,7 +32,7 @@
     "npm-run-all": "^4.1.2",
     "text-encoding": "^0.6.0",
     "webpack": "4.18.1",
-    "webpack-cli": "^2.0.13"
+    "webpack-cli": "^3.1.2"
   },
   "author": {
     "name": "Pine Mizune",