Add detect.py GIF video inference (#6410)

* Add detect.py GIF video inference

* Cleanup

utils/datasets.py

@@ -33,8 +33,8 @@ from utils.torch_utils import torch_distributed_zero_first
 
 # Parameters
 HELP_URL = 'https://github.com/ultralytics/yolov5/wiki/Train-Custom-Data'
-IMG_FORMATS = ['bmp', 'jpg', 'jpeg', 'png', 'tif', 'tiff', 'dng', 'webp', 'mpo']  # acceptable image suffixes
-VID_FORMATS = ['mov', 'avi', 'mp4', 'mpg', 'mpeg', 'm4v', 'wmv', 'mkv']  # acceptable video suffixes
+IMG_FORMATS = ['bmp', 'dng', 'jpeg', 'jpg', 'mpo', 'png', 'tif', 'tiff', 'webp']  # include image suffixes
+VID_FORMATS = ['avi', 'gif', 'm4v', 'mkv', 'mov', 'mp4', 'mpeg', 'mpg', 'wmv']  # include video suffixes
 DEVICE_COUNT = max(torch.cuda.device_count(), 1)
 
 # Get orientation exif tag