Update minimum ruby version to 2.5.
What does this MR do?
Updates the docs to indicate Ruby 2.5 is now required.
See https://gitlab.com/gitlab-org/gitlab-ce/issues/57350 for more reasons why it is.
Updates the docs to indicate Ruby 2.5 is now required.
See https://gitlab.com/gitlab-org/gitlab-ce/issues/57350 for more reasons why it is.