Bump eslint-config-prettier from 6.15.0 to 9.1.0 in /backend

Bumps [eslint-config-prettier](https://github.com/prettier/eslint-config-prettier) from 6.15.0 to 9.1.0.
- [Changelog](https://github.com/prettier/eslint-config-prettier/blob/main/CHANGELOG.md)
- [Commits](prettier/eslint-config-prettier@v6.15.0...v9.1.0)

---
updated-dependencies:
- dependency-name: eslint-config-prettier
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

backend/package.json

@@ -71,7 +71,7 @@
     "dockerode": "^3.3.1",
     "dotenv": "^16.0",
     "eslint": "^8.46.0",
-    "eslint-config-prettier": "^6.12.0",
+    "eslint-config-prettier": "^9.1.0",
     "eslint-plugin-prettier": "^5.0.0",
     "jest": "^27",
     "json-schema-to-typescript": "^13.0",