message: fix: mining bug caused by type changes in RPC
diff: @@ -169,8 +169,8 @@ impl Client {
  fn get_block_template(&self) -> impl Future<Item = BlockTemplate, Error = RpcError> {
  let method = "get_block_template".to_owned();
  let params = vec![
  - json!(self.config.cycles_limit),
  - json!(self.config.bytes_limit),
  + json!(self.config.cycles_limit.to_string()),
  + json!(self.config.bytes_limit.to_string()),
  json!(self.config.max_version),
  ];
  