Remove B type param (#1751)

Co-authored-by: Jonas Platte <[email protected]>
Co-authored-by: Michael Scofield <[email protected]>

axum-macros/tests/debug_handler/fail/extract_self_ref.rs

@@ -8,14 +8,13 @@ use axum_macros::debug_handler;
 struct A;
 
 #[async_trait]
-impl<S, B> FromRequest<S, B> for A
+impl<S> FromRequest<S> for A
 where
-    B: Send + 'static,
     S: Send + Sync,
 {
     type Rejection = ();
 
-    async fn from_request(_req: Request<B>, _state: &S) -> Result<Self, Self::Rejection> {
+    async fn from_request(_req: Request<axum::body::Body>, _state: &S) -> Result<Self, Self::Rejection> {
         unimplemented!()
     }
 }