Bump webpack from 4.27.1 to 4.28.3 in /js

Bumps [webpack](https://github.com/webpack/webpack) from 4.27.1 to 4.28.3.
- [Release notes](https://github.com/webpack/webpack/releases)
- [Commits](https://github.com/webpack/webpack/compare/v4.27.1...v4.28.3)

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

js/package.json

@@ -30,7 +30,7 @@
     "karma": "^3.1.4",
     "mini-css-extract-plugin": "^0.5.0",
     "uglifyjs-webpack-plugin": "^2.1.0",
-    "webpack": "^4.27.1",
+    "webpack": "^4.28.3",
     "webpack-cli": "^3.1.2",
     "webpack-merge": "^4.1.5"
   },