H3: fix clippy warnings

quinn-h3/src/client.rs

@@ -534,11 +534,8 @@ where
     ///
     /// The peer will receive a request error with `REQUEST_CANCELLED` code.
     pub fn cancel(&mut self) {
-        match self.state {
-            SendRequestState::Sending(ref mut send) => {
-                send.cancel();
-            }
-            _ => (),
+        if let SendRequestState::Sending(ref mut send) = self.state {
+            send.cancel();
         }
     }
 }

quinn-h3/src/data.rs

@@ -201,7 +201,7 @@ impl RecvData {
 
     pub fn reset(&mut self, err_code: ErrorCode) {
         if let Some(ref mut r) = self.recv {
-            r.reset(err_code.into());
+            r.reset(err_code);
         }
     }
 }

quinn-h3/src/headers.rs

@@ -61,7 +61,7 @@ impl SendHeaders {
     }
 
     pub fn reset(&mut self, err_code: ErrorCode) {
-        self.0.reset(err_code.into());
+        self.0.reset(err_code);
     }
 }