Make the create*Event methods return strings

[gr2m]

Follow up to copilot-extensions/github-models-extension#5 (comment).

I can't think of situations where we would need the structured data. Once we do, we can change it back, it's a problem when it's a problem.

[github-actions]

🎉 This issue has been resolved in version 4.0.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀