Update ci-testing.yml

[glenn-jocher]

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Enhanced the continuous integration workflow for more flexibility in triggering tests.

📊 Key Changes

• Added workflow_dispatch to the CI configuration.

🎯 Purpose & Impact

• Flexibility: Allows developers to manually trigger the CI tests whenever needed, not just on specific events or schedules.
• Improved Efficiency: Facilitates more control over the testing process, leading to faster identification and resolution of issues.