Update gridfs.js

src/server/service/file-uploader/gridfs.js

@@ -29,6 +29,7 @@ module.exports = function(crowi) {
   lib.deleteFile = async function(attachment) {
     let filenameValue = attachment.fileName;
     if (attachment.filePath != null) { // backward compatibility for v3.3.x or below
+      
       filenameValue = attachment.filePath;
     }