Tokenizer fast warnings (#2922)
* Remove warning when pad_to_max_length is not set.
Signed-off-by: Morgan Funtowicz <morgan@huggingface.co>
* Move RoberTa warning to RoberTa and not GPT2 base tokenizer.
Signed-off-by: Morgan Funtowicz <morgan@huggingface.co>
