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

Closes #310

Author: greenkeeper[bot]

package.json

@@ -54,7 +54,7 @@
     "style-loader": "^0.21.0",
     "styled-jsx": "^2.2.6",
     "webpack": "^4.8.3",
-    "webpack-cli": "^2.1.3",
+    "webpack-cli": "^3.1.2",
     "webpack-serve": "^1.0.2",
     "enzyme": "^2.4.1",
     "eslint-config-prettier": "^3.0.1",