fix compile errors in tests and examples

Dependencies

• [2] HDEDMPBT Client example
• [3] 2WEO7OZL Version updates: getting rid of anyhow + moving to Tokio 1.0
• [4] AWVLXGAW Removing anyhows on Windows
• [5] 7FRJYUI6 Reboot because of a bad change

Change contents

• replacement in thrussh-keys/src/lib.rs at line 747
  [3.54966]→[3.54966:55035](∅→∅)
  − let (_, buf) = client.sign_request(&public, buf).await?;
  [3.54966]

  [3.55035]
  + let (_, buf) = client.sign_request(&public, buf).await;

  + let buf = buf?;
• replacement in thrussh-keys/src/lib.rs at line 799
  [3.56531]→[3.56531:56597](∅→∅)
  − agent::server::serve(listener.incoming(), X {}).await
  [3.56531]

  [3.56597]
  + agent::server::serve(

  + Incoming {

  + listener: &mut listener,

  + },

  + X {},

  + )

  + .await
• replacement in thrussh-keys/src/lib.rs at line 818
  [3.57200]→[3.57200:57269](∅→∅)
  − let (_, buf) = client.sign_request(&public, buf).await?;
  [3.57200]

  [3.57269]
  + let (_, buf) = client.sign_request(&public, buf).await;

  + let buf = buf?;
• edit in thrussh-keys/src/lib.rs at line 826
  [3.57439]

  [3.57439]
  +

  + struct Incoming<'a> {

  + listener: &'a mut tokio::net::UnixListener,

  + }

  + impl futures::stream::Stream for Incoming<'_> {

  + type Item = Result<tokio::net::UnixStream, std::io::Error>;

  +

  + fn poll_next(

  + self: std::pin::Pin<&mut Self>,

  + cx: &mut std::task::Context<'_>,

  + ) -> std::task::Poll<Option<Self::Item>> {

  + let (sock, _addr) = futures::ready!(self.get_mut().listener.poll_accept(cx))?;

  + std::task::Poll::Ready(Some(Ok(sock)))

  + }

  + }
• replacement in thrussh/examples/client.rs at line 46
  [2.1441]→[2.1441:1475](∅→∅)
  − .await

  − .unwrap();
  [2.1441]

  [2.1475]
  + .await;

  + let auth_res = auth_res.unwrap();