Hi there 👋

I was playing with the **TelegramOperator** and stumbled upon a bug with the `text` field. It is supposed to be a template field but in reality the instance of the **TelegramOperator** does not have this attribute thus every time I try to execute code I get the error:

> AttributeError: 'TelegramOperator' object has no attribute 'text'

```python
TelegramOperator(
        task_id='send_message_telegram',
        telegram_conn_id='telegram_conn_id',
        text='Hello from Airflow!'
    )
```
tests/providers/telegram/operators/test_telegram.py
mock_telegram_hook.return_value = mock.Mock()
        mock_telegram_hook.return_value.send_message.return_value = True
        hook = TelegramOperator(
            telegram_conn_id='telegram_default',
            chat_id='-420913222',
            task_id='telegram',
            text="some non empty text",
        )
        hook.execute()
        mock_telegram_hook.assert_called_once_with(
            telegram_conn_id='telegram_default',
            chat_id='-420913222',
            token=None,
        )
        mock_telegram_hook.return_value.send_message.assert_called_once_with(
            {'text': 'some non empty text'},
        )
    def test_should_throw_exception_if_connection_id_is_none(self):