message: implement clippy suggestion not to use `assert_eq` on `()`
diff: @@ -112,7 +112,7 @@ fn with_retry_repeats_the_call_then_works() {
  let config = Config::default().unwrap();
  *config.shell() = Shell::from_write(Box::new(Vec::new()));
  let result = with_retry(&config, || results.pop().unwrap());
  - assert_eq!(result.unwrap(), ())
  + assert!(result.is_ok())
  }
  #[test]
  @@ -135,7 +135,7 @@ fn with_retry_finds_nested_spurious_errors() {
  let config = Config::default().unwrap();
  *config.shell() = Shell::from_write(Box::new(Vec::new()));
  let result = with_retry(&config, || results.pop().unwrap());
  - assert_eq!(result.unwrap(), ())
  + assert!(result.is_ok())
  }
  #[test]
  