Add unpdf for cloudflare support - pdfjs-dist gives ERRORS

https://airesearch.js.org/functions/convertPDFToHTML.html Adds footnote and headings. https://github.com/johannschopplich/pdfjs-serverless It is better bc it supports more environemnts. Current version wont compile, error Cannot find pdfjs-dist build Added PR: https://github.com/opengovsg/pdf2md/pull/96/files