fix: use std::os::fd instead of std::os::wasi (#380)

fixes #379

Author: Stebalien

src/file/mod.rs

@@ -5,10 +5,10 @@ use std::fs::{self, File, OpenOptions};
 use std::io::{self, Read, Seek, SeekFrom, Write};
 use std::mem;
 use std::ops::Deref;
-#[cfg(unix)]
-use std::os::unix::io::{AsFd, AsRawFd, BorrowedFd, RawFd};
 #[cfg(target_os = "wasi")]
-use std::os::wasi::io::{AsFd, AsRawFd, BorrowedFd, RawFd};
+use std::os::fd::{AsFd, AsRawFd, BorrowedFd, RawFd};
+#[cfg(unix)] // we don't use std::os::fd because that's not available on rust 1.63.
+use std::os::unix::io::{AsFd, AsRawFd, BorrowedFd, RawFd};
 #[cfg(windows)]
 use std::os::windows::io::{AsHandle, AsRawHandle, BorrowedHandle, RawHandle};
 use std::path::{Path, PathBuf};