fix: not negotiate h2 when using native-tls backend with feature native-tls-alpn enabled

[cxw620]

fix: not negotiate h2 when using native-tls backend with feature native-tls-alpn enabled.

[cxw620]

I've tested this PR with the following minimum example:

#[tokio::main]
async fn main() {
    // tracing_subscriber::registry().with(fmt::layer()).init();
    let client = reqwest::Client::builder()
        .use_native_tls()
        // .use_rustls_tls()
        // .proxy(reqwest::Proxy::all("socks5://127.0.0.1:20023").unwrap()) // without patch from this PR, enable proxy may cause panic with error `hyper::Error(Parse(Version))`. Unknown reason.
        .build()
        .unwrap();
    let version = client
        .get("https://google.com/")
        .send()
        .await
        .unwrap()
        .version();
    println!("{:?}", version); // should get HTTP/2.0 instead of HTTP/1.1
}

[dependencies]
reqwest = { version = "0.11.25", features = [
    # "rustls-tls",
    "native-tls-alpn",
    "socks",
] }
tokio = { version = "1.36.0", features = ["full"] }

[cxw620]

@seanmonstar Could you provide an update on this PR? Any feedback or comments on it? Thanks :D