convert darknet to onnx
pip install git+ssh://git@github.com/wep21/yolo_onnx_converter.git
yolo_onnx_converter <your darknet cfg file> <your darknet weights file> <your label file> -o <output onnx file> --yolo_type <"yolov3", "yolov4", "yolov4-tiny">