Changed
- Add unit tests with using Moto mock library
- Update code to be compatible with the latest PyFilesystems2 version (2.4)
- Add `config_arg` parameter to `S3FS` constructor. Can be used to customize S3 client behavior as documented in [botocore.config](https://botocore.amazonaws.com/v1/documentation/api/latest/reference/config.html)
- Fix race condition when `S3FS` is accessed from multiple theads.
- Pass `upload_args` to `copy()` method (required when server-side encryption is enforced)
- Fix bug with incomplete upload to S3 when the file object is destroyed by garbage collector without calling `close()` method
- Convert boto-specific exceptions to `FSError` when error is encountered in `remove()` method