Fix model downloads for the case where this repo is used as a submodule

[mikel-brostrom]

I added your repo as a submodule in mine. However, when running attempt_load from a folder above

.
├── yolov7/
├── track.py  # this calls the functionality in yolov7/

I get:

Downloading https://github.com/WongKinYiu/yolov7/releases/download/yolov7/yolov7.pt to /home/xyz/yolov5_strongsort_osnet/weights/yolov7.pt...
Download error: HTTP Error 404: Not Found
ERROR: Download failure: /home/xyz/yolov5_strongsort_osnet/weights/yolov7.pt missing, try downloading from https://github.com/WongKinYiu/yolov7/releases/

Are you planning to fix this? My intention is to use the detector in combination with a tracking module

[WongKinYiu]

Could it run well on u5 branch?

[mikel-brostrom]

Doesn't look like it @WongKinYiu ,

https://github.com/WongKinYiu/yolov7/blob/a6215c0dbb8a6b06cbf7a5698ebe1e65f6540f5c/utils/downloads.py#L55

[mikel-brostrom]

Got it working here: https://github.com/mikel-brostrom/yolov7