Bump webpack-merge from 5.8.0 to 5.9.0

Bumps [webpack-merge](https://github.com/survivejs/webpack-merge) from 5.8.0 to 5.9.0.
- [Changelog](https://github.com/survivejs/webpack-merge/blob/develop/CHANGELOG.md)
- [Commits](https://github.com/survivejs/webpack-merge/commits)

---
updated-dependencies:
- dependency-name: webpack-merge
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

package-lock.json

@@ -84,7 +84,7 @@
     "webpack-bundle-analyzer": "^4.9.1",
     "webpack-cli": "^4.7.2",
     "webpack-dev-server": "^3.11.2",
-    "webpack-merge": "^5.8.0"
+    "webpack-merge": "^5.9.0"
   },
   "peerDependencies": {
     "monaco-editor": "^0.21.3",