title: Airflow ECS - override the image tag when using EcsOperator
body: <p>I'm using ECS Operator in Airflow and I want to run task_definition with a specific image tag.</p>
  <p>ECS Operator is using <code>run_task()</code> method in <code>boto3</code>, and it is possible to overrides some of the task definition parameters.
  I can't find a way to override the <code>image:tag</code>.</p>
  <p>Does anyone know if it is possible to run a task with a specific image version? or other technics how to control which version of the image to use without using the latest or the tag that is defined in the task definition?</p>