[nexa] Open-Sourced GPTZero

It uses GPTv2 Perplexity Model from Huggingface to find total perplexity of the sentence. Later, we break it into individual sentences based on some delimiters, and find individual perplexity per line and find total average perplexities. The average perplexities is then passed through certain threshold, and if it crosses it, it becomes human-centric, otherwise the text is generated by an AI. https://www.indiehackers.com/post/open-sourced-gptzero-788e8c9d1a A.