Fix TypeError: no implicit conversion of Hash into String
Fix TypeError: no implicit conversion of Hash into String

Use old version of the `Job` initializer that only accepted a JSON
payload `String`.

The new initializer has been introduced from version 3.1, see
https://github.com/mperham/sidekiq/commit/2513884aa02fce184e7ef5b955401936eb29df94.

NuckChorris/sidekiq-debounce,hummingbird-me/sidekiq-debounce