message: fix wasi test template code
diff: @@ -54,9 +54,10 @@ macro_rules! assert_wasi_output {
  let expected_output = include_str!($expected);
  assert!(
  - assert_cond,
  + output.contains(expected_output),
  "Output: `{}` does not contain expected output: `{}`",
  - output, expected_output
  + output,
  + expected_output
  );
  }};
  }
  