Make Middleware always Send + Sync + 'static

src/request.rs

@@ -7,8 +7,8 @@ use crate::body::Payload;
 use crate::header::{self, Header};
 use crate::middleware::MiddlewareNext;
 use crate::unit::{self, Unit};
+use crate::Response;
 use crate::{agent::Agent, error::Error};
-use crate::{Middleware, Response};
 
 pub type Result<T> = std::result::Result<T, Error>;
 
@@ -143,11 +143,7 @@ impl Request {
         let response = if !self.agent.state.middleware.is_empty() {
             // Clone agent to get a local copy with same lifetime as Payload
             let agent = self.agent.clone();
-            let chain = &mut agent
-                .state
-                .middleware
-                .iter()
-                .map(|mw| mw.as_ref() as &dyn Middleware);
+            let chain = &mut agent.state.middleware.iter().map(|mw| mw.as_ref());
 
             let request_fn = Box::new(request_fn);