Bump webpack-cli from 3.3.12 to 4.6.0 in /www

Bumps [webpack-cli](https://github.com/webpack/webpack-cli) from 3.3.12 to 4.6.0.
- [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/v3.3.12...webpack-cli@4.6.0)

Signed-off-by: dependabot[bot] <support@github.com>

www/package.json

@@ -33,7 +33,7 @@
     "copy-webpack-plugin": "^5.0.0",
     "hello-wasm-pack": "^0.1.0",
     "webpack": "^4.29.3",
-    "webpack-cli": "^3.1.0",
+    "webpack-cli": "^4.6.0",
     "webpack-dev-server": "^3.1.5"
   }
 }