Bump webpack from 4.22.0 to 4.23.1 in /js

Bumps [webpack](https://github.com/webpack/webpack) from 4.22.0 to 4.23.1.
- [Release notes](https://github.com/webpack/webpack/releases)
- [Commits](https://github.com/webpack/webpack/compare/v4.22.0...v4.23.1)

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

js/package.json

@@ -30,7 +30,7 @@
     "karma": "^3.1.0",
     "mini-css-extract-plugin": "^0.4.4",
     "node-sass": "^4.9.4",
-    "webpack": "^4.22.0",
+    "webpack": "^4.23.1",
     "webpack-cli": "^3.1.2",
     "webpack-merge": "^4.1.4"
   },