GitLab

Related to https://gitlab.com/gitlab-com/gl-infra/infrastructure/issues/5313

This is in keeping with the CE/EE changes.

Other version bumps were happening implicitly in Omnibus builds.

This fixes a number of CVEs and aligns dependencies with
GitLab CE.

Full list of changes:
https://github.com/sinatra/sinatra/blob/master/CHANGELOG.md

This reflects the version used in CE.

Full list of changes:
https://github.com/resque/redis-namespace/blob/master/CHANGELOG.md

This was identified in https://gitlab.com/gitlab-org/omnibus-gitlab/issues/3772.

Since there's no real harm in shipping two Sidekiq versions, let's just update
to the latest version but lock the version down a bit more. This matches
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/21624.

As mentioned in https://gitlab.com/gitlab-org/omnibus-gitlab/issues/3772#note_99878357,
the version number was not updated.

Relates to gitlab-org/omnibus-gitlab#3698

Closes gitlab-org/omnibus-gitlab#3462