build(deps-dev): bump tsx in /services/backend in the development group

Bumps the development group in /services/backend with 1 update: [tsx](https://github.com/privatenumber/tsx).


Updates `tsx` from 4.23.12 to 4.23.13
- [Release notes](https://github.com/privatenumber/tsx/releases)
- [Changelog](https://github.com/privatenumber/tsx/blob/master/release.config.cjs)
- [Commits](https://github.com/privatenumber/tsx/compare/v4.23.12...v4.23.13)

---
updated-dependencies:
- dependency-name: tsx
  dependency-version: 4.23.13
  dependency-type: direct:development
  update-type: version-update:semver-patch
  dependency-group: development
...

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

services/backend/package.json

@@ -34,7 +34,7 @@
     "@types/node": "^26.4.0",
     "@types/pg": "^8.23.1",
     "@types/ws": "^8.18.1",
-    "tsx": "^4.23.12",
+    "tsx": "^4.23.13",
     "typescript": "^7.0.2",
     "vitest": "latest"
   }