use file_path_with_name

lib/tallty_import_export/export.rb

@@ -54,8 +54,9 @@ module TalltyImportExport
         file_path = File.join(Rails.root, 'public', 'export')
         FileUtils.mkdir_p(file_path) unless Dir.exist?(file_path)
         file_name = "#{Time.now.strftime('%Y%m%d%H%M%S')}#{@filename}.xlsx"
-        pack.serialize(File.join(file_path, file_name))
-        return "/export/#{file_name}"
+        file_path_with_name = File.join(file_path, file_name)
+        pack.serialize(file_path_with_name)
+        return file_path_with_name
       end
     end