Fix transport imports

Author: alexrudy

tonic/src/transport/service/connector.rs

@@ -14,12 +14,6 @@ use super::super::BoxFuture;
 use super::io::BoxedIo;
 #[cfg(feature = "tls")]
 use super::tls::TlsConnector;
-use http::Uri;
-#[cfg(feature = "tls")]
-use std::fmt;
-use std::task::{Context, Poll};
-use tower::make::MakeConnection;
-use tower_service::Service;
 
 pub(crate) struct Connector<C> {
     inner: C,