title: Delete django data without RuntimeWarning: DateTimeField received a naive datetime
body: <p>I am trying to delete 3 years old data in my python django db. Here is code:</p>
  <pre><code>from datetime import datetime
  from dateutil.relativedelta import relativedelta
  
  def db_cleanup():
      cleanup_start = datetime.utcnow().date()
      three_years_ago = cleanup_start - relativedelta(years=3)
  
      MyData.objects.filter(create_date__lt=three_years_ago).delete()
  </code></pre>
  <p>however I receive RuntimeWarning: <strong>DateTimeField received a naive datetime</strong> . How to do it properly?</p>