chore: bump gitlab-zoekt to v1.13.1 on 18-11-stable

Summary

Bumps gitlab-zoekt-indexer from v1.13.0 to v1.13.1 on 18-11-stable for GitLab 18.11 (SM).

v1.13.1 backports the schemaVersion bump that triggers a force reindex for customers affected by the force-push detection fix.

Backport chain for 18.11 (SM)

1. ✅ gitlab-zoekt-indexer — tagged v1.13.1 on 18-11-stable with schemaVersion bump
2. ⭐ gitlab-org/build/CNG — this MR, builds cng/gitlab-zoekt:v1.13.1 on 18-11-stable
3. ⏳ gitlab-org/gitlab — MR on 18-11-stable-ee bumping GITLAB_ZOEKT_VERSION to v1.13.1

Related: gitlab-org/gitlab-zoekt-indexer#120