Fix a hyperparameter value in gpt-neox

[jaeminSon]

In GPTNeoXConfig, ‘use_parallel_residual' argument was not initially present. (huggingface/transformers@71e6027)

After 4 months, the 'use_parallel_residual' argument was introduced. (huggingface/transformers@226b0e4)

Models that were trained and uploaded using the previous commit do not include the "use_parallel_residual" argument in their "config.json" files, thus, output the following errors when converting to a ggml format.

File "../examples/gpt-neox/convert-h5-to-ggml.py", line 61, in <module> fout.write(struct.pack("i", hparams["use_parallel_residual"])) KeyError: 'use_parallel_residual'

Such models include
https://huggingface.co/EleutherAI/polyglot-ko-1.3b ,
https://huggingface.co/EleutherAI/polyglot-ko-5.8b ,
https://huggingface.co/EleutherAI/polyglot-ko-12.8b

Since the default value for the parameter is True (https://github.com/huggingface/transformers/blob/d941f07a4e3bc7b61b7afbd25d6e2e8427fccc6d/src/transformers/models/gpt_neox/configuration_gpt_neox.py#L29), which corresponds to the implementations in the previous commit, it should be set to True.