build(deps): Bump postcss and css-loader in /qtoggleserver/frontend

Bumps [postcss](https://github.com/postcss/postcss) to 8.5.6 and updates ancestor dependency [css-loader](https://github.com/webpack-contrib/css-loader). These dependencies need to be updated together.


Updates `postcss` from 7.0.39 to 8.5.6
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@7.0.39...8.5.6)

Updates `css-loader` from 3.6.0 to 7.1.2
- [Release notes](https://github.com/webpack-contrib/css-loader/releases)
- [Changelog](https://github.com/webpack-contrib/css-loader/blob/master/CHANGELOG.md)
- [Commits](webpack/css-loader@v3.6.0...v7.1.2)

---
updated-dependencies:
- dependency-name: postcss
  dependency-version: 8.5.6
  dependency-type: indirect
- dependency-name: css-loader
  dependency-version: 7.1.2
  dependency-type: direct:development
...

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

Author: dependabot[bot]

qtoggleserver/frontend/package-lock.json

@@ -22,7 +22,7 @@
         "@babel/preset-env": "*",
         "@babel/eslint-parser": "*",
         "babel-loader": "^8",
-        "css-loader": "^3",
+        "css-loader": "^7",
         "eslint": "^9",
         "expose-loader": "^1",
         "file-loader": "*",