Add model_type to config.json

Without an explicit value of model_type in config.json, Sagemaker HuggingFaceModel predict api throws following error

"""ModelError: An error occurred (ModelError) when calling the InvokeEndpoint operation: Received client error (400) from primary with message "{
"code": 400,
"type": "InternalServerException",
"message": "Unrecognized model in /.sagemaker/mms/models/stabilityai__japanese-stablelm-base-alpha-7b. Should have a `model_type` key in its config.json, or contain one of the following strings in its name: vision-encoder-decoder, trocr, fnet, segformer, gptj, layoutlmv2, beit, rembert, visual_bert, canine, roformer, clip, bigbird_pegasus, deit, luke, detr, gpt_neo, big_bird, speech_to_text_2, speech_to_text, vit, wav2vec2, m2m_100, convbert, led, blenderbot-small, retribert, ibert, mt5, t5, mobilebert, distilbert, albert, bert-generation, camembert, xlm-roberta, pegasus, marian, mbart, megatron-bert, mpnet, bart, blenderbot, reformer, longformer, roberta, deberta-v2, deberta, flaubert, fsmt, squeezebert, hubert, bert, openai-gpt, gpt2, transfo-xl, xlnet, xlm-prophetnet, prophetnet, xlm, ctrl, electra, speech-encoder-decoder, encoder-decoder, funnel, lxmert, dpr, layoutlm, rag, tapas, splinter, sew-d, sew, unispeech-sat, unispeech"
}
"""

config.json

@@ -26,5 +26,6 @@
   "use_bias_in_mlp": false,
   "use_cache": true,
   "use_parallel_residual": true,
-  "vocab_size": 65536
+  "vocab_size": 65536,
+  "model_type" : "gpt-neo"
 }