Bug: SORT always same iou_threshold

[denguir]

Hi there,

I think there is a small bug here
iou_threshold is hard coded to 0.3, I think you wanted something more like

matches, unmatched_detections, unmatched_tracks = assign_tracks2detection_iou(
                bbox_tracks, bbox_detections, iou_threshold=self.iou_threshold)

[adipandas]

@denguir Thanks for the pull request. I approved it.