Fix test

Author: dalance

src/libproc/proc_pid.rs

@@ -529,7 +529,7 @@ pub trait ListPIDInfo {
 ///         if let Ok(fds) = listpidinfo::<ListFDs>(pid, info.pbsd.pbi_nfiles as usize) {
 ///             for fd in &fds {
 ///                 let fd_type = ProcFDType::from(fd.proc_fdtype);
-///                 println!("File Descriptor: {}, Type: {}", fd.proc_fd, fd_type);
+///                 println!("File Descriptor: {}, Type: {:?}", fd.proc_fd, fd_type);
 ///             }
 ///         }
 ///     }