message: Fix StateProof validation for string expected value.
diff: @@ -504,7 +504,13 @@ fn _parse_reply_for_proof_value(json_msg: &SJsonValue, data: Option<String>, par
  }
  }
  - Ok(Some(value.to_string()))
  + let value_str = if let Some(value) = value.as_str() {
  + value.to_owned()
  + } else {
  + value.to_string()
  + };
  +
  + Ok(Some(value_str))
  } else {
  Ok(None)
  }
  