Upgrade to Ruby 2.5.3
- EE MR: gitlab-ee!8069 (merged)
- Gitaly MR: gitaly!942 (merged)
- omnibus-gitlab MR: omnibus-gitlab!2806 (merged)
- GDK MR: gitlab-development-kit!550 (merged)
Attempt to update google-protobuf for migration-paths. Because the one we were using aren't compatible with Ruby 2.5.3, and it'll be troublesome to switch Ruby. Upgrading google-protobuf will be much easier.
All of them will need to be updated for Ruby 2.5.3.