Crate: export with the async-h1 client by default

This should be stable enough.

Refs: #217

Cargo.toml

@@ -14,7 +14,7 @@ edition = "2018"
 [features]
 # when the default feature set is updated, verify that the `--features` flags in
 # `.github/workflows/ci.yaml` are updated accordingly
-default = ["native-client", "middleware-logger", "encoding"]
+default = ["h1-client", "middleware-logger", "encoding"]
 h1-client = ["wasm-client", "http-client/h1_client"]
 native-client = ["curl-client", "wasm-client", "http-client/native_client"]
 curl-client = ["http-client/curl_client"]