Update config.json

remove `"xla_device": true` to remove warning.

config.json

@@ -21,6 +21,5 @@
  "num_hidden_layers": 12,
  "pad_token_id": 1,
  "type_vocab_size": 1,
- "vocab_size": 50265,
- "xla_device": true
+ "vocab_size": 50265
 }