Weights & Biases integration for inference

[soumik12345]

Modifications added in this PR:

• Download the model automatically from the release based on the model file
• Download the image for inference from a URL
• Added support for logging inference results to Weights & Biases.

Sample Workspace: https://wandb.ai/geekyrakshit/yolov6-integration-test

Sample Usage:

python tools/infer.py --weights yolov6s.pt --source data/images/ --wandb_project <wandb-project-name> --wandb_entity <wandb-entity-name>

[soumik12345]

cc: @Chilicyy

[Chilicyy]

Thanks for your contribution! We'll check and verify the code asap.