Bump prettier from 2.8.7 to 2.8.8 in /backend

Bumps [prettier](https://github.com/prettier/prettier) from 2.8.7 to 2.8.8.
- [Release notes](https://github.com/prettier/prettier/releases)
- [Changelog](https://github.com/prettier/prettier/blob/main/CHANGELOG.md)
- [Commits](prettier/prettier@2.8.7...2.8.8)

---
updated-dependencies:
- dependency-name: prettier
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

backend/package.json

@@ -101,7 +101,7 @@
     "jest-light-runner": "^0.4.1",
     "mongodb-memory-server": "^8.12.2",
     "nodemon": "^2.0.22",
-    "prettier": "2.8.7",
+    "prettier": "2.8.8",
     "supertest": "^6.3.3",
     "ts-jest": "^29.1.0",
     "ts-node": "^10.9.1",