Update ci-testing.yml

[glenn-jocher]

copilot:all

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Improved GitHub CI notifications and link checking robustness for the Ultralytics YOLOv3 repository.

📊 Key Changes

• Slack notifications for failed tests now trigger only for pushes and scheduled events on the main ultralytics/yolov3 repo.
• Increased retry wait time from 30 to 60 seconds for the link checker to decrease the likelihood of false positives.
• The link checker now uses a GitHub token for improved authentication when verifying links.

🎯 Purpose & Impact

• These changes aim to reduce notification noise by only sending Slack alerts for relevant events on the main repository, helping maintainers to focus on important failures.
• By increasing the wait time for retries, the likelihood of the link checker service falsely flagging a link as broken due to timeouts or rate limits is reduced.
• The addition of the GitHub token provides the link checker tool more access, potentially reducing false negatives and thereby increasing the accuracy of link verification.
• Ultimately, these updates will streamline the notification process and link checking, improving the overall efficiency and reliability of the repository's maintenance for both maintainers and contributors.