Please add support for CSV & JSON

[apuatcfbd]

CSV & JSON are two of the most common file formats when we work with web applications. Unfortunately, the lib doesn't support that. Support for CSV is very much needed.

[ivanvanderbyl]

I needed this as well but realised that it is a very difficult problem. I would suggest first looking at other heuristics such as file extension. Outside of that the only really reliable way to check the file is a library such as magika from Google. Currently only available for Python, Rust, and Node, but is actively being worked on for Go.