fix model on cuda

examples/run_openai_gpt.py

@@ -135,6 +135,7 @@ def main():
     tokenizer = OpenAIGPTTokenizer.from_pretrained(args.model_name, special_tokens=special_tokens)
     special_tokens_ids = list(tokenizer.convert_tokens_to_ids(token) for token in special_tokens)
     model = OpenAIGPTDoubleHeadsModel.from_pretrained(args.model_name, num_special_tokens=len(special_tokens))
+    model.to(device)
 
     # Load and encode the datasets
     def tokenize_and_encode(obj):