`Logster::Logger#chained` is now readable in new version of logster.

config/initializers/100-logster.rb

@@ -100,6 +100,6 @@ RailsMultisite::ConnectionManagement.each_connection do
 end
 
 if Rails.configuration.multisite
-  chained = Rails.logger.instance_variable_get(:@chained)
+  chained = Rails.logger.chained
   chained && chained.first.formatter = RailsMultisite::Formatter.new
 end

config/initializers/101-lograge.rb

@@ -106,7 +106,7 @@ if (Rails.env.production? && SiteSetting.logging_provider == 'lograge') || ENV["
 
       # Remove ActiveSupport::Logger from the chain and replace with Lograge's
       # logger
-      Rails.logger.instance_variable_get(:@chained).pop
+      Rails.logger.chained.pop
       Rails.logger.chain(config.lograge.logger)
     end
   end