no need to send date header in client

The date header is optional for clients, but also seems to be
discouraged. It's so rare so maybe leave it to the user.

https://tools.ietf.org/html/rfc7231#section-7.1.1.2
> A user agent MAY send a Date…

The older RFC https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.18
> Clients SHOULD only send a Date header field in messages that include an entity-body,
> as in the case of the PUT and POST requests, and even then it is optional. A client
> without a clock MUST NOT send a Date header field in a request.

Author: gdamjan

src/client/encode.rs

@@ -6,8 +6,6 @@ use http_types::{Method, Request};
 
 use std::pin::Pin;
 
-use crate::date::fmt_http_date;
-
 /// An HTTP encoder.
 #[doc(hidden)]
 #[derive(Debug)]
@@ -89,11 +87,6 @@ impl Encoder {
             //      https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Trailer
         }
 
-        let date = fmt_http_date(std::time::SystemTime::now());
-        buf.write_all(b"date: ").await?;
-        buf.write_all(date.as_bytes()).await?;
-        buf.write_all(b"\r\n").await?;
-
         for (header, values) in req.iter() {
             for value in values.iter() {
                 let val = format!("{}: {}\r\n", header, value);

tests/fixtures/request-add-date.txt

@@ -1,7 +1,6 @@
 POST / HTTP/1.1
 host: localhost:8080
 content-length: 5
-date: {DATE}
 content-type: text/plain; charset=utf-8
 
 hello

tests/fixtures/request-with-connect.txt

@@ -2,5 +2,4 @@ CONNECT example.com:443 HTTP/1.1
 host: example.com
 proxy-connection: keep-alive
 content-length: 0
-date: {DATE}