add support for sidekiq 8.*

[dimroc]

Allow those of us on sidekiq 8.* to use Desiru.

Without change, it errors with incompatible dependencies:

❯ bundle add desiru
Fetching gem metadata from https://gems.contribsys.com/..
Fetching gem metadata from https://rubygems.org/........
Resolving dependencies...
Could not find compatible versions

Because sidekiq-throttled >= 2.0.0 depends on sidekiq >= 8.0
  and every version of desiru depends on sidekiq ~> 7.2,
  sidekiq-throttled >= 2.0.0 is incompatible with desiru >= 0.
So, because Gemfile depends on sidekiq-throttled ~> 2.0
  and Gemfile depends on desiru >= 0,
  version solving has failed.

With change, we can bundle add