Preserve case of server error messages

Server errors can contain case-sensitive values like subject names which
can cause confusion if not displayed in their original case.

async-nats/src/lib.rs

@@ -1294,7 +1294,7 @@ impl ServerError {
  fn new(error: String) -> ServerError {
  match error.to_lowercase().as_str() {
  "authorization violation" => ServerError::AuthorizationViolation,
- other => ServerError::Other(other.to_string()),
+ _ => ServerError::Other(error.to_string()),
  }
  }
 }