style(lib): address clippy code style warnings

* Remove unnecessary return statements.

* Combine identical `match` arms.

* Collapse nested conditional.

* Use `assert_ne` where applicable.

* Lifetime elision.

src/client/connect.rs

@@ -103,7 +103,6 @@ impl Service for HttpConnector {
         let port = match uri.port() {
             Some(port) => port,
             None => match uri.scheme() {
-                Some("http") => 80,
                 Some("https") => 443,
                 _ => 80,
             },