style(lib): address most clippy lints

src/client/conn.rs

@@ -345,8 +345,8 @@ where
         };
 
         Parts {
-            io: io,
-            read_buf: read_buf,
+            io,
+            read_buf,
             _inner: (),
         }
     }
@@ -363,9 +363,9 @@ where
     /// and [`try_ready!`](https://docs.rs/futures/0.1.25/futures/macro.try_ready.html)
     /// to work with this function; or use the `without_shutdown` wrapper.
     pub fn poll_without_shutdown(&mut self, cx: &mut task::Context<'_>) -> Poll<crate::Result<()>> {
-        match self.inner.as_mut().expect("already upgraded") {
-            &mut ProtoClient::H1(ref mut h1) => h1.poll_without_shutdown(cx),
-            &mut ProtoClient::H2(ref mut h2) => Pin::new(h2).poll(cx).map_ok(|_| ()),
+        match *self.inner.as_mut().expect("already upgraded") {
+            ProtoClient::H1(ref mut h1) => h1.poll_without_shutdown(cx),
+            ProtoClient::H2(ref mut h2) => Pin::new(h2).poll(cx).map_ok(|_| ()),
         }
     }