Update train.py with yaml.SafeLoader (ultralytics#1972)

train.py

@@ -479,7 +479,7 @@ def train(hyp, opt, device, tb_writer=None, wandb=None):
         assert os.path.isfile(ckpt), 'ERROR: --resume checkpoint does not exist'
         apriori = opt.global_rank, opt.local_rank
         with open(Path(ckpt).parent.parent / 'opt.yaml') as f:
-            opt = argparse.Namespace(**yaml.load(f, Loader=yaml.FullLoader))  # replace
+            opt = argparse.Namespace(**yaml.load(f, Loader=yaml.SafeLoader))  # replace
         opt.cfg, opt.weights, opt.resume, opt.batch_size, opt.global_rank, opt.local_rank = '', ckpt, True, opt.total_batch_size, *apriori  # reinstate
         logger.info('Resuming training from %s' % ckpt)
     else:
@@ -503,7 +503,7 @@ def train(hyp, opt, device, tb_writer=None, wandb=None):
 
     # Hyperparameters
     with open(opt.hyp) as f:
-        hyp = yaml.load(f, Loader=yaml.FullLoader)  # load hyps
+        hyp = yaml.load(f, Loader=yaml.SafeLoader)  # load hyps
 
     # Train
     logger.info(opt)