Updated sidekiq Gemfile.lock for celluloid error

Should (hopefully fix issue with: "Mysql2::Error: This connection is still waiting for a result, try again once you have the result:"

https://github.com/mperham/sidekiq/pull/954
https://github.com/celluloid/celluloid/pull/268

Change-Id: I4daa65b6b6f9de20975d95ba07ffab103ec03204