conf: used the updated version to format logs in Sidekiq

config/initializers/sidekiq.rb

@@ -5,7 +5,7 @@
 
 Sidekiq.configure_server do |config|
   config.redis = { url: ENV['REDIS_URL'] }
-  config.log_formatter = Sidekiq::Logger::Formatters::JSON.new
+  config.logger.formatter = Sidekiq::Logger::Formatters::JSON.new
 end
 
 Sidekiq.configure_client do |config|