title: Ubuntu 20.04 upgrade, Python missing libffi.so.6
body: <p>I recently upgraded my OS to Ubuntu 20.04 LTS.</p>
  <p>Now when I try to import a library like Numpy in Python, I get the following error:</p>
  <pre><code>ImportError: libffi.so.6: cannot open shared object file: No such file or directory
  </code></pre>
  <p>I tried installing the <code>libffi</code> package, but apt can't locate it :</p>
  <pre><code>sudo apt-get install libffi
  Reading package lists... Done
  Building dependency tree       
  Reading state information... Done
  E: Unable to locate package libffi
  </code></pre>