Getting TLS to work with Rust client

Hi, I have bene trying to call: 
```
cargo run --example raw -- --pd "[endpoint]" --ca ca.crt --cert tls.cert --key tls.key
```
But getting: "PD cluster failed to response". 
However,
```
curl -k --cacert ca.crt --cert tls.crt --key tls.key [endpoint/pd/api/v1/members]
```
will work. 
I did try to modify `raw.rs` to use `v1` API, but getting the same output.