Switch serde dependency to serde_core (#3477)

axum-extra/src/json_lines.rs

@@ -9,7 +9,7 @@ use axum::{
 use bytes::{BufMut, BytesMut};
 use futures_util::stream::{BoxStream, Stream, TryStream, TryStreamExt};
 use pin_project_lite::pin_project;
-use serde::{de::DeserializeOwned, Serialize};
+use serde_core::{de::DeserializeOwned, Serialize};
 use std::{
     convert::Infallible,
     io::{self, Write},
@@ -173,7 +173,7 @@ where
 
 #[cfg(test)]
 mod tests {
-    use super::*;
+    use super::JsonLines;
     use crate::test_helpers::*;
     use axum::{
         routing::{get, post},
@@ -181,8 +181,8 @@ mod tests {
     };
     use futures_util::StreamExt;
     use http::StatusCode;
-    use serde::Deserialize;
-    use std::error::Error;
+    use serde::{Deserialize, Serialize};
+    use std::{convert::Infallible, error::Error};
 
     #[derive(Serialize, Deserialize, PartialEq, Eq, Debug)]
     struct User {