Bump the vitest group with 2 updates

Bumps the vitest group with 2 updates: [@vitest/ui](https://github.com/vitest-dev/vitest/tree/HEAD/packages/ui) and [vitest](https://github.com/vitest-dev/vitest/tree/HEAD/packages/vitest).


Updates `@vitest/ui` 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/ui)

Updates `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/ui"
  dependency-version: 4.1.6
  dependency-type: direct:development
  update-type: version-update:semver-patch
  dependency-group: vitest
- dependency-name: vitest
  dependency-version: 4.1.6
  dependency-type: direct:development
  update-type: version-update:semver-patch
  dependency-group: vitest
...

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

frontend/package.json

@@ -38,11 +38,11 @@
     "@types/react": "^19.0.0",
     "@types/react-dom": "^19.0.0",
     "@vitejs/plugin-react": "^6.0.1",
-    "@vitest/ui": "^4.1.5",
+    "@vitest/ui": "^4.1.6",
     "tailwindcss": "^4.3.0",
     "typescript": "~6.0.3",
     "vite": "^8.0.12",
     "vite-plugin-pwa": "^1.3.0",
-    "vitest": "^4.1.5"
+    "vitest": "^4.1.6"
   }
 }