build(deps-dev): bump vitest from 4.1.5 to 4.1.6 in /frontend (GreedyBear-Project#1333)

Bumps [vitest](https://github.com/vitest-dev/vitest/tree/HEAD/packages/vitest) from 4.1.5 to 4.1.6.
- [Release notes](https://github.com/vitest-dev/vitest/releases)
- [Commits](https://github.com/vitest-dev/vitest/commits/v4.1.6/packages/vitest)

---
updated-dependencies:
- dependency-name: vitest
  dependency-version: 4.1.6
  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>

Author: dependabot[bot]

frontend/package-lock.json

@@ -56,6 +56,6 @@
     "prettier": "^3.8.3",
     "stylelint": "^17.11.0",
     "vite": "^8.0.10",
-    "vitest": "^4.1.5"
+    "vitest": "^4.1.6"
   }
 }