title: How do I auto run extension install command on Heroku when provisioning DB using pipelines?
body: <p>I'm using the Heroku Pipelines feature to auto create a review app whenever I create a new PR in github. This will provision a new DB for you and migrate all your database schema. When migrating this schema I receive this error:</p>
  
  <pre><code>AttributeError: 'DatabaseOperations' object has no attribute 'geo_db_type'
  </code></pre>
  
  <p>I want to use PostGIS which means I need to run <code>CREATE EXTENSION postgis;</code> 
  on the db after it's automatically provisioned. My hunch is that I'm getting this error because the extension isn't installed yet by the time it runs <code>python manage.py migrate</code>. How would I run this in an automated way when it's building my review app? </p>