Fix broken web_api_extention tests
Fix broken web_api_extention tests

The content_type helper method was replaced in https://github.com/mperham/sidekiq/commit/ed485e47e47aa52583470fb4313e8a88c51d5f15#diff-05434c79c3a83cc66923dafdd86fc5d4.

Fixed by using the `type` `attr_accessor `

davydovanton/sidekiq-statistic,davydovanton/sidekiq-statistic,davydovanton/sidekiq-history,davydovanton/sidekiq-history,davydovanton/sidekiq-statistic