NEW Model GPT-JX

### Model description request to add a new model gpt-jx-3b to the transformer library as well as request to create a custom model class, class names an be found in the below .txt files as well as at the below of the description, weights are present in hugging face model hub but made public for now, ["alien-ai/gpt-jx-3b"](https://huggingface.co/alien-ai/gpt-jx-3b) --id_repo. Just a little summary of the model has been provided in the repo.Currently the repo only contains pytorch_model.bin file and no files other than that. we provide you the code for modelling.py ,configuration.py and tokenization.py in .txt format [modelling_gptjx.txt](https://github.com/huggingface/transformers/files/12428050/modelling_gptjx.txt) [config.txt](https://github.com/huggingface/transformers/files/12428124/config.txt) [tokenization.txt] (https://github.com/huggingface/transformers/files/12428249/tokenization.txt) please check the files before proceeding. Make Sure to Set class names: GPTJXForCausalLM, GPTJXModel, GPTJXConfig, GPTJXTokenizer. Sorry, we are too busy right now so, i was not able to write the description properly. Please Check it Out Yourself. Please create the new model class as soon as possible ### Open source status - [X] The model implementation is available - [X] The model weights are available ### Provide useful links for the implementation Authors will be revealed later. repo-- ["alien-ai/gpt-jx-3b"](https://huggingface.co/alien-ai/gpt-jx-3b)