Also update builds.sr.ht hook to use this
GitHub compatible webhook payloads would be nice
I don't think that strictly matching GitHub-compatibility is truly needed. Isn't it better to design your own webhooks and webhooks API cleanly, flexibly and extensibly, and only provide GitHub-compatible bridge on top of it?
Well, If you think GitHub webhooks are great, enough for your needs, etc., then sure, no need to reinvent the wheel, but constraining from the beginning just to be compatible with something is not always a good approach. BitBucket has its own webhooks too, so it may be good thing to check them too.
The main rationale behind using GitHub-compatible webhooks is for compatability with existing software that is compatible with GitHub webhooks.