build(deps): bump zod in /services/backend in the production group

Bumps the production group in /services/backend with 1 update: [zod](https://github.com/colinhacks/zod).


Updates `zod` from 4.5.2 to 4.5.4
- [Release notes](https://github.com/colinhacks/zod/releases)
- [Commits](https://github.com/colinhacks/zod/compare/v4.5.2...v4.5.4)

---
updated-dependencies:
- dependency-name: zod
  dependency-version: 4.5.4
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: production
...

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

services/backend/package.json

@@ -26,7 +26,7 @@
     "pino": "^10.3.1",
     "prom-client": "^15.1.3",
     "ws": "^8.21.3",
-    "zod": "^4.5.2"
+    "zod": "^4.5.4"
   },
   "devDependencies": {
     "@biomejs/biome": "latest",