tsort: remove unused TsortError::IO variant

Author: dragutreis

src/uu/tsort/src/tsort.rs

@@ -148,9 +148,6 @@ enum TsortError {
     #[error("{input}: {message}", input = .0, message = translate!("tsort-error-loop"))]
     Loop(String),
 
-    /// Wrapper for bubbling up IO errors
-    #[error("{0}")]
-    IO(#[from] io::Error),
     /// Read error.
     #[error("{}", translate!("tsort-error-read", "error" => strip_errno(.0)))]
     Read(io::Error),