build(deps-dev): bump mini-css-extract-plugin in /frontend (#2033)

Bumps [mini-css-extract-plugin](https://github.com/webpack-contrib/mini-css-extract-plugin) from 2.7.6 to 2.7.7.
- [Release notes](https://github.com/webpack-contrib/mini-css-extract-plugin/releases)
- [Changelog](https://github.com/webpack-contrib/mini-css-extract-plugin/blob/master/CHANGELOG.md)
- [Commits](webpack-contrib/mini-css-extract-plugin@v2.7.6...v2.7.7)

---
updated-dependencies:
- dependency-name: mini-css-extract-plugin
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

frontend/package.json

@@ -30,7 +30,7 @@
     "eslint-plugin-promise": "^6.1.1",
     "eslint-plugin-vue": "^9.20.1",
     "html-webpack-plugin": "^5.6.0",
-    "mini-css-extract-plugin": "^2.7.6",
+    "mini-css-extract-plugin": "^2.7.7",
     "process": "^0.11.10",
     "style-loader": "^3.3.4",
     "vue-loader": "^15.11.1",