Update Gitaly dependency to v14.9.0-rc1
This MR updates the Gitaly dependency's version to v14.9.0-rc1. This version contains a fix for connection hangs when gRPC closes an unhealthy connection to Gitaly. This bug likely never affected gitlab-shell due to it not reusing connections to Gitaly. To avoid problems in the future if that is ever done, let's update the dependency.
Related to: gitlab#351425 (closed)
Edited by Sami Hiltunen