chore(deps-dev): bump @vue/cli-service from 3.8.3 to 3.8.4 in /frontend (#785)

Bumps [@vue/cli-service](https://github.com/vuejs/vue-cli/tree/HEAD/packages/@vue/cli-service) from 3.8.3 to 3.8.4.
- [Release notes](https://github.com/vuejs/vue-cli/releases)
- [Changelog](https://github.com/vuejs/vue-cli/blob/dev/CHANGELOG.md)
- [Commits](https://github.com/vuejs/vue-cli/commits/v3.8.4/packages/@vue/cli-service)

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

frontend/package.json

@@ -27,7 +27,7 @@
   "devDependencies": {
     "@vue/cli-plugin-babel": "^3.8.0",
     "@vue/cli-plugin-eslint": "^3.8.0",
-    "@vue/cli-service": "^3.8.3",
+    "@vue/cli-service": "^3.8.4",
     "babel-eslint": "^10.0.1",
     "eslint": "^5.16.0",
     "eslint-plugin-vue": "^5.2.2",