title: can not install psycopg2 on macOS Catalina
body: <p>when installing psycopg2 in my Django project </p>
  
  <pre><code>pip install psycopg2==2.7.*
  </code></pre>
  
  <p>I get this error :</p>
  
  <pre><code>psycopg/psycopgmodule.c:689:18: error: incomplete definition of type 'struct _is'
  </code></pre>
  
  <p>I tried the answer to the following question: <a href="https://stackoverflow.com/questions/59065263/is-there-any-problem-installing-psycopg2-in-virtualenv-on-macos-catalina-with-po">Is there any problem installing psycopg2 in virtualenv on MacOS catalina with PostgreSQL 12.1 installed?</a>
   but I still get the same error</p>