title: Send csv with airflow
body: <p>Hi i'm trying to send a file with airflow (composer) csv stored in gcp storage but i can't attach it.
  I get the error &quot;No such file or directory: 'gs://bucket-test/test.csv'&quot;</p>
  <p>the mail is sent correctly if I do not attach a file.</p>
  <p>another question is: can I create a csv without saving it to storage? and send it directly</p>
  <pre><code>output_file = 'gs://bucket-test/test.csv'
  
  email_summary = email_operator.EmailOperator(
      task_id='email_summary',
      to=['test@gmail.com'],
      subject='Sample email',
      html_content=&quot;&quot;&quot;
      test_01. 
      &quot;&quot;&quot;,
      files=[output_file])
  </code></pre>