chore(backend): bump vitest from 2.1.9 to 3.2.3 in /services/backend

Bumps [vitest](https://github.com/vitest-dev/vitest/tree/HEAD/packages/vitest) from 2.1.9 to 3.2.3.
- [Release notes](https://github.com/vitest-dev/vitest/releases)
- [Commits](https://github.com/vitest-dev/vitest/commits/v3.2.3/packages/vitest)

---
updated-dependencies:
- dependency-name: vitest
  dependency-version: 3.2.3
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

services/backend/package.json

@@ -61,7 +61,7 @@
     "ts-node": "^10.9.2",
     "typescript": "^5.8.3",
     "typescript-eslint": "^8.33.0",
-    "vitest": "^2.1.8"
+    "vitest": "^3.2.3"
   },
   "overrides": {
     "glob": "^10.0.0",