Introduce support for missing GitHub event types

[tuunit]

Problem

Currently, the action only serializes a fixed set of GitHub event types (IssueCommentEvent, IssuesEvent, PullRequestEvent, ReleaseEvent). Other event types, such as PullRequestReviewEvent, PushEvent, ForkEvent, WatchEvent, and more, are ignored and do not show up in the activity readme.

Proposal

• Add serialization functions for meaningful additional event types (e.g., PullRequestReviewEvent, PushEvent, ForkEvent, etc.).
  https://docs.github.com/en/rest/using-the-rest-api/github-event-types?apiVersion=2022-11-28
• Ignore noisy or non-informative events like WatchEvents