remove stable_mir::error::Error derive Serialize

Author: Stephen Skeirik

compiler/stable_mir/src/error.rs

@@ -6,7 +6,6 @@
 
 use std::fmt::{Debug, Display, Formatter};
 use std::{fmt, io};
-use serde::Serialize;
 
 macro_rules! error {
      ($fmt: literal $(,)?) => { Error(format!($fmt)) };
@@ -28,7 +27,7 @@ pub enum CompilerError<T> {
 }
 
 /// A generic error to represent an API request that cannot be fulfilled.
-#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
+#[derive(Clone, Debug, Eq, PartialEq)]
 pub struct Error(pub(crate) String);
 
 impl Error {