Update yolo.py with yaml.SafeLoader (ultralytics#1970)

models/yolo.py

@@ -71,7 +71,7 @@ def __init__(self, cfg='yolov5s.yaml', ch=3, nc=None):  # model, input channels,
             import yaml  # for torch hub
             self.yaml_file = Path(cfg).name
             with open(cfg) as f:
-                self.yaml = yaml.load(f, Loader=yaml.FullLoader)  # model dict
+                self.yaml = yaml.load(f, Loader=yaml.SafeLoader)  # model dict
 
         # Define model
         ch = self.yaml['ch'] = self.yaml.get('ch', ch)  # input channels