Parsing tsconfig doesn't work if the file contains comments

I run into issues where this action fails if the typescript config file contains. I think this is because TypeScript uses [JSONC](https://github.com/muhammadmuzzammil1998/jsonc). You might be able to fix this by using TypeScript's JSON compiler, like this comment suggests: https://www.reddit.com/r/typescript/comments/8na5vb/comment/dzus6a9/