fix(http): remove connection-specific header field

https://datatracker.ietf.org/doc/html/rfc7540#section-8.1.2.2

src/net.rs

@@ -1,20 +1,13 @@
 use std::time::Duration;
 
 fn default_reqwest_settings() -> reqwest::ClientBuilder {
-  // maybe we should configure it by ourselves
-  use reqwest::header::{HeaderMap, CONNECTION};
-
-  let mut headers = HeaderMap::new();
-  headers.insert(CONNECTION, "keep-alive".parse().unwrap());
 
   let connect_timeout = Duration::from_secs(10);
   let timeout = connect_timeout + Duration::from_secs(24);
 
   reqwest::Client::builder()
     .connect_timeout(connect_timeout)
     .timeout(timeout)
-    .tcp_nodelay(true)
-    .default_headers(headers)
 }
 pub fn client_from_config() -> reqwest::Client {
   use crate::config::CONFIG;