chore(deps): update dependency webpack-cli to v6

Author: renovate[bot]

package.json

@@ -104,7 +104,7 @@
     "uglifyjs-webpack-plugin": "2.2.0",
     "url-loader": "2.3.0",
     "webpack": "4.47.0",
-    "webpack-cli": "3.3.12",
+    "webpack-cli": "6.0.0",
     "webpack-dev-server": "3.11.3"
   },
   "config": {