Update webpack-cli requirement from 3.1.2 to 3.2.1 (#3850)

Updates the requirements on [webpack-cli](https://github.com/webpack/webpack-cli) to permit the latest version.
- [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/commits)

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

package.json

@@ -240,7 +240,7 @@
 		"web-push": "3.3.3",
 		"webfinger.js": "2.7.0",
 		"webpack": "4.28.3",
-		"webpack-cli": "3.1.2",
+		"webpack-cli": "3.2.1",
 		"websocket": "1.0.28",
 		"ws": "6.1.2",
 		"xev": "2.0.1"