Resque::Plugins::MultiStepTask causes FrozenError

I updated my project to Ruby 3.3.0 and there it is recommended to use frozen string literals. After that I get the `FrozenError` if I try to create a `MultiStepTask`:

```ruby
> Resque::Plugins::MultiStepTask.create('importer'.freeze)
resque-multi-step-2.0.9/lib/resque/plugins/multi_step_task.rb:62:in `create': can't modify frozen String: "importer" (FrozenError)
```