Update Gitlab Shell version to 14.18.0
What does this MR do and why?
Related MR: Release v14.18.0 (gitlab-shell!722 - merged)
- Perform HTTP request to primary on Geo push
- sshd: exclude gssapi when building without cgo
- Add DNS discovery support for Gitaly/Praefect
- Add bin/gitlab-sshd as an explicit Makefile target