Update GITLAB_SHELL_VERSION

What does this MR do?

Update GITLAB_SHELL_VERSION to continue with the plan to change the parameters passed around GitLab components to allow for independence of mount points.

Are there points in the code the reviewer needs to double check?

No

Why was this MR needed?

See https://gitlab.com/gitlab-org/gitlab-shell/merge_requests/130#note_28747613

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitaly/issues/201