get_multiplexed_async_std_connection complains about missing tokio runtime

[UgnilJoZ]

I try to instantiate a multiplexed async connection like the following:

#[async_std::main]
async fn main() {
    redis::Client::open("redis://127.1/")
        .unwrap()
        .get_multiplexed_async_std_connection()
        .await
        .unwrap();
}

In version 0.22, the second unwrap panics with thread 'main' panicked at 'there is no reactor running, must be called from the context of a Tokio 1.x runtime', /home/…/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.21.2/src/net/addr.rs:219:48:

[dependencies]
redis = {version = "0.22", features = ["async-std-comp"]}
async-std = { version = "1", features = [ "attributes" ] }

The panic vanishes if I change "version" to 0.21.

[djc]

I bisected this, it seems the originating commit is from #606. So in this PR it seems I forgot that we couldn't depend on Tokio directly, and we need to implement DNS lookup with async-std in the case async-std-comp is enabled.

Would you be able to submit a PR for this?

[UgnilJoZ]

Thanks, this is a fast response! I'll push a PR.