Support the merge_group event

[JamieMagee]

Describe the feature

Users started to receive payloads for this event (See #76). However, the details of this event are not yet in the public documentation¹. We should add the full event model once the public documentation is available.

Footnotes

1. https://docs.github.com/en/developers/webhooks-and-events/webhooks/webhook-events-and-payloads ↩

[mntlty]

@JamieMagee when creating the webhook I also created the open api specification for it. I believe this isn't public due to published: false here https://github.com/github/github/blob/master/app/api/description/webhooks/merge-group/checks-requested.yaml#L69 but I'm not familiar with how changes to the public docs are made. Can you provide guidance on what is necessary for that to go live?

fyi @willsmythe

[JamieMagee]

Unfortunately, I'm not familiar either. I just consume the API 😅

Maybe @nickfloyd knows?

[wolfy1339]

The event docs are now public, and I have created schemas over in octokit/webhooks#681