Bump the gitaly version to 1.7.0

What does this MR do?

    Changelog from gitaly:

    ** v1.7.0

    **** Added
    - Add an RPC that allows repository size to be reduced by bulk-removing internal references
      https://gitlab.com/gitlab-org/gitaly/merge_requests/990

    ** v1.6.0

    **** Other
    - Clean up invalid keep-around refs when performing housekeeping
      https://gitlab.com/gitlab-org/gitaly/merge_requests/992

    ** v1.5.0

    **** Added
    - Add tls configuration to gitaly golang server
      https://gitlab.com/gitlab-org/gitaly/merge_requests/932

    **** Fixed
    - Fix TLS client code on macOS
      https://gitlab.com/gitlab-org/gitaly/merge_requests/994

    **** Other
    - Update to latest goimports formatting
      https://gitlab.com/gitlab-org/gitaly/merge_requests/993

    ** v1.4.0

    **** Added
    - Link and Unlink RPCs
      https://gitlab.com/gitlab-org/gitaly/merge_requests/986

    ** v1.3.0

    *** Other
    - Remove unused bridge_exceptions method
      https://gitlab.com/gitlab-org/gitaly/merge_requests/987
    - Clean up process documentation
      https://gitlab.com/gitlab-org/gitaly/merge_requests/984

What are the relevant issue numbers?

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/44431

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer