HMAC-based security for webhooks

We've added support for HMAC-based security in our outgoing webhooks. Both those set up through our conventional webhooks functionality, as well as those set up via automations. This is a fairly standard practice at this point and lets you confirm that any incoming webhook that you ingest is actually coming from us and not just coming from a random user who happens to know that you have a webhook handler exposed to the given input. You can read the documentation here.