Add more must_use attributes (#2846)

… so people get a warning when they accidentally add a semicolon after the response expression in a handler function.

Also update changelogs of axum-core, axum-extra.

axum-extra/CHANGELOG.md

@@ -7,7 +7,9 @@ and this project adheres to [Semantic Versioning].
 
 # Unreleased
 
-- None.
+- **added:** The `response::Attachment` type ([#2789])
+
+[#2789]: https://github.com/tokio-rs/axum/pull/2789
 
 # 0.9.3 (24. March, 2024)
 

axum-extra/src/response/attachment.rs

@@ -33,8 +33,8 @@ use tracing::error;
 /// # Note
 ///
 /// If you use axum with hyper, hyper will set the `Content-Length` if it is known.
-///
 #[derive(Debug)]
+#[must_use]
 pub struct Attachment<T> {
     inner: T,
     filename: Option<HeaderValue>,