Don't force HTTP2 support about hyper-rustls

[Arnavion]

To save other people the time to investigate this: If you're using a hyper::Client, and you only enabled the http1 feature of hyper and not the http2 feature, and you see a channel closed error from hyper from executing some (but not necessarily all) of your client requests, this issue may be why. To be sure, enable trace logging for rustls and see if there's a log indicating it selected HTTP/2 during ALPN right before the request failed:

[DEBUG rustls::client::hs] ALPN protocol is Some(b"h2")

For requests that succeed, you'd instead see ALPN protocol is None or ALPN protocol is Some(b"http/1.1")

[kahlil29]

Just to clarify, if I'm using the rusoto crate with the rustls feature enabled (I think it depends on hyper-rustls), is there a way for me to know if I'm hitting this issue?
i.e. (Can I) How do I enable logging that would enable me to narrow down the issue or confirm that this issue affects me?