error when trying to send a url filebox

[hcfw007]

https://github.com/wechaty/puppet-whatsapp/blob/04b542667626d589563180443651378df85af98a/src/puppet-mixin/message.ts#L248-L249

When a url filebox is converted to JSON, the key to get url should be 'url' instead of 'remoteUrl'