fix: upgrade css-loader from 6.7.3 to 6.8.1

Snyk has created this PR to upgrade css-loader from 6.7.3 to 6.8.1.

See this package in npm:
https://www.npmjs.com/package/css-loader

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

@@ -26,7 +26,7 @@
     "babel-plugin-prismjs": "^2.1.0",
     "babel-polyfill": "^6.26.0",
     "clean-webpack-plugin": "^4.0.0",
-    "css-loader": "^6.7.3",
+    "css-loader": "^6.8.1",
     "css-minimizer-webpack-plugin": "^5.0.1",
     "eslint": "^8.46.0",
     "eslint-config-prettier": "^8.10.0",