Bump version to 0.38.3, following GeeseFS

- Make long directory listings faster (remove O(N^2))
- Fix long directory listings where some files could be skipped due to inode expiration
- Remove extra empty COPY requests when metadata is not changed
- Add --fsync-on-close option for synchronous s3fs-like mode
- Fix --disable-xattr error code
- Do not try to switch between STANDARD and COLD based on the object size