Support guaranteed for current stable and previous major versions.
So with release of Sidekiq 7, Sidekiq 6 are supported and Sidekiq 5 is no longer supported.
So with release of Sidekiq 8, Sidekiq 7 are supported and Sidekiq 6 is no longer supported.
So with release of Sidekiq 9, Sidekiq 8 are supported and Sidekiq 7 is no longer supported.