fix permission in attachment cache worker

app/workers/attachment_cache_worker.rb

 class AttachmentCacheWorker
-  require 'fileutils'
   include Sidekiq::Worker
 
   sidekiq_options queue: :attachment_cache
@@ -16,7 +15,10 @@ class AttachmentCacheWorker
 
     file = client.bitstreams.retrieve(id: @attachment.id_dspace).open
     begin
-      @attachment.update(cache_link: cache_link) if FileUtils.mkdir_p(directory_root) && FileUtils.mv(file.path, file_root)
+      FileUtils.mkdir_p(directory_root)
+      FileUtils.mv(file.path, file_root)
+      FileUtils.chmod 0644, file_root.to_s, verbose: true
+      @attachment.update(cache_link: cache_link)
     ensure
       file.close if !file.nil? && File.exist?(file.path)
     end