S3 upload_fileobj parameter Callback doesn't support asynchronous function callbacks

[zent1n0]

I'm writing a small feature to provide a progress showing when uploading file onto s3. In my callback, the function writes progress to a message queue, so later the message will be sent to event stream with FastAPI StreamingResponse. The function puts message into an asyncio.Queue, therefore it must be asynchronous one.
As the module provides an asynchronous version of boto3, I guess it should be fine if we adjust the processing logic with Callback, so it could also accept a coroutine to be run nonblockingly.

[terricain]

Yeah, raise a PR and I'll have a look