fix: upgrade webpack-merge from 5.8.0 to 5.9.0

Snyk has created this PR to upgrade webpack-merge from 5.8.0 to 5.9.0.

See this package in npm:
https://www.npmjs.com/package/webpack-merge

See this project in Snyk:
https://app.snyk.io/org/woodpile37/project/044862aa-1005-4f2f-af06-341513c0e0a2?utm_source=github&utm_medium=referral&page=upgrade-pr

Author: snyk-bot

frontend/package.json

@@ -48,7 +48,7 @@
     "webpack": "^5.76.0",
     "webpack-cli": "^5.1.4",
     "webpack-dev-server": "^4.15.1",
-    "webpack-merge": "^5.8.0"
+    "webpack-merge": "^5.9.0"
   },
   "dependencies": {
     "chartist": "^1.3.0",