Bump tonic and prost dependencies

[erebe]

• When using a newer version of prost (in my case 0.9) the crate complains that it can find the prost::Message trait.
  Bumping the version of tonic and prost fix the issue

[erebe]

gentle bump :)

[teohhanhui]

And now tonic is at 0.8.0 🙈

[erebe]

I still use the project and bumped the version for the 0.8.0 to work, but haven't bothered to update the PR as the author seem absent.

Regarding mocking, I saw that tonic propose some way to mock directly in their project
https://github.com/hyperium/tonic/blob/master/examples/src/mock/mock.rs

but I haven't tested myself, as I already have done my tests with this project.
Maybe worth considering instead of relying on this dead project

[teohhanhui]

Yes, indeed, I follow the same example and realized I have no need for this project.

Additionally, for streaming requests / streaming responses do something like:

let (req_tx, req_rx) = mpsc::channel(128);
let req_stream = ReceiverStream::new(req_rx);
let mut res_stream = client.some_streaming_method(Request::new(req_stream)).await?;

let req = SomeRequest { ... };
req_tx.send(req).await?;
let res = res_stream.message().await;
assert!(res.is_ok());
let res = res.unwrap();
assert!(res.is_some());