refactor: default to beam search v1

Author: gongel

examples/machine_translation/transformer/predict.py

@@ -84,9 +84,7 @@ def do_predict(args):
         eos_id=args.eos_idx,
         beam_size=args.beam_size,
         max_out_len=args.max_out_len,
-        use_ft=not args.without_ft,
-        beam_search_version='v2',
-        alpha=0.6)
+        use_ft=not args.without_ft)
 
     # Load the trained model
     assert args.init_from_params, (