Update dependency webpack-cli to v3.2.1 (#298)

Author: renovate[bot]

package-lock.json

@@ -62,7 +62,7 @@
     "stylelint": "9.9.0",
     "stylelint-config-wordpress": "13.1.0",
     "webpack": "4.28.3",
-    "webpack-cli": "3.2.0"
+    "webpack-cli": "3.2.1"
   },
   "engines": {
     "node": "10.15.0",