Bump webpack-cli from 3.3.12 to 4.0.0

Bumps [webpack-cli](https://github.com/webpack/webpack-cli) from 3.3.12 to 4.0.0.
- [Release notes](https://github.com/webpack/webpack-cli/releases)
- [Changelog](https://github.com/webpack/webpack-cli/blob/master/CHANGELOG.md)
- [Commits](https://github.com/webpack/webpack-cli/compare/[email protected])

Signed-off-by: dependabot[bot] <[email protected]>

package.json

@@ -49,7 +49,7 @@
     "terser-webpack-plugin": "^4.0.0",
     "webpack": "^4.42.0",
     "webpack-chrome-extension-reloader": "^1.3.0",
-    "webpack-cli": "^3.3.11"
+    "webpack-cli": "^4.0.0"
   },
   "ava": {
     "babel": true,