FIX: retrieve original filename from s3 object's content disposition header

lib/s3_inventory.rb

@@ -85,10 +85,11 @@ class S3Inventory
       if result.count >= 1
         key = result[0]["key"]
         data = @s3_helper.object(key).data
+        filename = (data.content_disposition&.match(/filename=\"(.*)\"/) || [])[1]
 
         upload_id = Upload.create!(
           user_id: Discourse.system_user.id,
-          original_filename: "",
+          original_filename: filename || File.basename(key),
           filesize: data.content_length,
           url: File.join(Discourse.store.absolute_base_url, key),
           sha1: sha1,