title: How to import Secret in airflow?
body: <p>I was trying to use a module in airflow called Secrets to pass secrets to KubernetesOperator in Airflow.
  It should be imported as <code>from airflow.contrib.kubernetes.secret import Secret</code></p>
  <p>But I'm getting an error
  <code>ModuleNotFoundError: No module named 'airflow.contrib.kubernetes'</code></p>
  <p>I have tried to install apache-airflow kubernetes package <code>pip install apache-airflow[kubernetes]</code>
  but this did not help.</p>