Repository: lettre/lettre (language: rust)

Issue:
async-std access to AsyncSmtpTransport isn't possible in latest release
**Describe the bug**
`AsyncSmtpTransport` is not accessible with the following features:
```toml
features = ["async-std", "async-std1", "async-std1-rustls-tls"]
```

It says that you need to have the `tokio02` or `tokio1` features enabled, however, I am not using the tokio async runtime, i'm using the async-std async runtime.

**Expected behavior**
To be able to use `AsyncSmtpTransport` with the `async-std` feature flags.

**Environment (please complete the following information):**
- Lettre version: `0.10.0-beta.2`
- OS: `macOS`

**Additional context**
I'm following the examples in the repo, however I suspect that it works in your examples folder because the examples have the tokio examples also present.



Discussion / hints:
Is there a chance that this can be fixed before the `0.10.0` release?

Fix patch:
diff --git a/src/lib.rs b/src/lib.rs
index d10f9b01c..86cdc5133 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -93,7 +93,7 @@ pub use crate::transport::sendmail::AsyncSendmailTransport;
 pub use crate::transport::sendmail::SendmailTransport;
 #[cfg(all(
     feature = "smtp-transport",
-    any(feature = "tokio02", feature = "tokio1")
+    any(feature = "tokio02", feature = "tokio1", feature = "async-std1")
 ))]
 pub use crate::transport::smtp::AsyncSmtpTransport;
 #[doc(inline)]


Test patch: