Acuity will post to /webhook when a new appointment is scheduled
or an existing appointment is rescheduled or canceled.
Acuity won't be able to access 127.0.0.1:8000 so you'll either
have to take our word for it, or try this on your server! Set your callback
location under the
Webhook integration.
All arguments are sent as application/x-www-form-urlencoded content.
scheduled rescheduled or canceled depending on the action that initiated the webhook call