Python version tests 3.7-3.10

[glenn-jocher]

Python version CI tests with 3.6, 3.7, 3.8, 3.9, 3.10 added to the matrix.

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Expanding Python version testing and adjusting dependencies for CI in YOLOv5's workflow.

📊 Key Changes

• Python Versions Tested: Extended the range of Python versions under CI from just 3.9 to include 3.6.8, 3.7, 3.8, and 3.10.
• Dependencies Update: Removed direct installation of onnx while setting up the testing environment.

🎯 Purpose & Impact

• Broader Compatibility: By testing across multiple Python versions, ensures YOLOv5's compatibility and stability across different environments.
• Dependency Management: Removing onnx from the install command suggests a deprioritization or change in how the library is used or installed, which could streamline the setup process for CI.

This update should not directly affect end-users' experience but rather ensures the developers that YOLOv5 will work consistently across more versions of Python. This could reduce bugs and compatibility issues for users working with different Python environments. 🐍🔧🧪

[glenn-jocher]

Closing as now satisfied by #7996