fix(http2): remove host header when using http2 (#3516)

Co-authored-by: Rob Ede <robjtede@icloud.com>

awc/CHANGES.md

@@ -5,6 +5,7 @@
 - Update `brotli` dependency to `7`.
 - Prevent panics on connection pool drop when Tokio runtime is shutdown early.
 - Minimum supported Rust version (MSRV) is now 1.75.
+- Do not send `Host` header on HTTP/2 requests, as it is not required, and some web servers may reject it.
 
 ## 3.5.1
 

awc/src/client/h2proto.rs

@@ -12,7 +12,7 @@ use h2::{
     SendStream,
 };
 use http::{
-    header::{HeaderValue, CONNECTION, CONTENT_LENGTH, TRANSFER_ENCODING},
+    header::{HeaderValue, CONNECTION, CONTENT_LENGTH, HOST, TRANSFER_ENCODING},
     request::Request,
     Method, Version,
 };
@@ -97,7 +97,7 @@ where
             // TODO: consider skipping other headers according to:
             //       https://datatracker.ietf.org/doc/html/rfc7540#section-8.1.2.2
             // omit HTTP/1.x only headers
-            CONNECTION | TRANSFER_ENCODING => continue,
+            CONNECTION | TRANSFER_ENCODING | HOST => continue,
             CONTENT_LENGTH if skip_len => continue,
             // DATE => has_date = true,
             _ => {}