Bump webpack from 3.11.0 to 4.1.1 in /WcaOnRails

Bumps [webpack](https://github.com/webpack/webpack) from 3.11.0 to 4.1.1.
- [Release notes](https://github.com/webpack/webpack/releases)
- [Commits](webpack/webpack@v3.11.0...v4.1.1)

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

WcaOnRails/package.json

@@ -34,7 +34,7 @@
     "sass-loader": "^6.0.7",
     "simplemde": "^1.11.2",
     "style-loader": "^0.20.3",
-    "webpack": "^3.11.0",
+    "webpack": "^4.1.1",
     "webpack-manifest-plugin": "^1.3.2",
     "webpack-merge": "^4.1.2",
     "whatwg-fetch": "^2.0.3"