Allow the Write API to accept an IO or StringIO object

[ksouthworth]

As far as I know, the Write API only accepts a File object. It would be nice if I could pass in any IO or StringIO object instead, for writing the CSV into a stream / memory.

My use case is I want to stream a CSV out from a Rails 8 controller action, without having to manage Tempfiles or having to create Files on disk in the process.