remove cv2.imread() call from video_test.py

This throws an error because it tries to load a video as an image, and removing it makes everything work normally. I'm guessing it's just leftover from reusing some test_single_image.py code.

Author: matthew-jack

video_test.py

@@ -64,8 +64,6 @@
 
     for i in range(video_frame_cnt):
         ret, img_ori = vid.read()
-
-        img_ori = cv2.imread(args.input_image)
         if args.letterbox_resize:
             img, resize_ratio, dw, dh = letterbox_resize(img_ori, args.new_size[0], args.new_size[1])
         else: