feat: enables github webhooks

[jayhack]

Adds Github webhook types and enables this syntax:

app = CodegenApp(name="github", image=base_image, modal_api_key="")


@app.github.event("pull_request:opened")
def handle_mention(event: PullRequestOpenedEvent):
    logger.info("[PULL_REQUEST:OPENED] Received pull request opened event")
    logger.info(f"PR #{event.number} opened: {event.pull_request.title}")
    logger.info(f"By user: {event.sender.login}")


@app.github.event("pull_request:labeled")
def handle_labeled(event: PullRequestLabeledEvent):
    logger.info("[PULL_REQUEST:LABELED] Received pull request labeled event")
    logger.info(f"PR #{event.number} labeled with: {event.label.name}")
    logger.info(f"PR title: {event.pull_request.title}")


@app.github.event("push")
def handle_push(event: PushEvent):
    logger.info("[PUSH] Received push event")
    logger.info(f"login: {event.sender.login}")
    logger.info(f"repo: {event.repository.name}")
    ```

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

✅ All tests successful. No failed tests found.

Additional details and impacted files

[github-actions]

🎉 This PR is included in version 0.19.0 🎉

The release is available on GitHub release

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