Added TF OpenAi GPT1 Sequence Classification (#9105)
* TF OpenAI GPT Sequence Classification
* Update src/transformers/models/openai/modeling_tf_openai.py
Co-authored-by: Lysandre Debut <lysandre@huggingface.co>
Co-authored-by: Lysandre Debut <lysandre@huggingface.co>
