fix(?): call flush() after writing, just in case

src/client/mod.rs

@@ -118,6 +118,7 @@ impl Client {
         // Write URL, then CRLF
         stream.write_all(url_str.as_bytes()).await?;
         stream.write_all(b"\r\n").await?;
+        stream.flush().await?;
 
         let status = {
             let mut buf: [u8; 3] = [0, 0, 0]; // 2 digits, space