Allow REDIS_URL to be set with ENV vars
user
```ruby
Sidekiq.configure_server do |config|
  config.redis = { url: ENV['REDIS_URL'] || 'redis://localhost:6379/12' }
end

Sidekiq.configure_client do |config|
  config.redis = { url: ENV['REDIS_URL'] || 'redis://localhost:6379/12' }
end
```
assistant