chore: Update to 2021 edition (#1188)

examples/src/blocking/client.rs

@@ -21,7 +21,7 @@ struct BlockingClient {
 impl BlockingClient {
     pub fn connect<D>(dst: D) -> Result<Self, tonic::transport::Error>
     where
-        D: std::convert::TryInto<tonic::transport::Endpoint>,
+        D: TryInto<tonic::transport::Endpoint>,
         D::Error: Into<StdError>,
     {
         let rt = Builder::new_multi_thread().enable_all().build().unwrap();

examples/src/mock/mock.rs

@@ -1,4 +1,3 @@
-use std::convert::TryFrom;
 use tonic::{
     transport::{Endpoint, Server, Uri},
     Request, Response, Status,

examples/src/uds/client.rs

@@ -5,7 +5,6 @@ pub mod hello_world {
 }
 
 use hello_world::{greeter_client::GreeterClient, HelloRequest};
-use std::convert::TryFrom;
 #[cfg(unix)]
 use tokio::net::UnixStream;
 use tonic::transport::{Endpoint, Uri};