Bump Rust edition to 2021 and a few crates (#18608)

* bump Rust edition to 2021, update a few creates

* bump Rust edition to 2021, update a few creates

samples/client/others/rust/hyper/emptyObject/src/apis/mod.rs

@@ -29,19 +29,19 @@ impl From<(hyper::StatusCode, hyper::body::Body)> for Error {
 
 impl From<http::Error> for Error {
     fn from(e: http::Error) -> Self {
-        return Error::Http(e)
+        Error::Http(e)
     }
 }
 
 impl From<hyper::Error> for Error {
     fn from(e: hyper::Error) -> Self {
-        return Error::Hyper(e)
+        Error::Hyper(e)
     }
 }
 
 impl From<serde_json::Error> for Error {
     fn from(e: serde_json::Error) -> Self {
-        return Error::Serde(e)
+        Error::Serde(e)
     }
 }
 

samples/client/others/rust/hyper/emptyObject/src/lib.rs

@@ -1,9 +1,6 @@
 #![allow(unused_imports)]
 #![allow(clippy::too_many_arguments)]
 
-#[macro_use]
-extern crate serde_derive;
-
 extern crate serde;
 extern crate serde_json;
 extern crate url;

samples/client/others/rust/hyper/emptyObject/src/models/empty_object.rs

@@ -9,6 +9,7 @@
  */
 
 use crate::models;
+use serde::{Deserialize, Serialize};
 
 #[derive(Clone, Default, Debug, PartialEq, Serialize, Deserialize)]
 pub struct EmptyObject {