title: How to update Certbot version?
body: <p>I am running <code>certbot --apache</code> but I get the following error:</p>
  
  <pre><code>Starting new HTTPS connection (1): acme-v01.api.letsencrypt.org
  Obtaining a new certificate
  Performing the following challenges:
  Client with the currently selected authenticator does not support any 
  combination of challenges that will satisfy the CA.
  </code></pre>
  
  <p>Version installed is <code>0.10.2</code> on Debian 8.10</p>
  
  <p>I would like to upgrade to 0.21.0 which should fix the issue <a href="https://community.letsencrypt.org/t/certbot-0-21-0-release/50725" rel="noreferrer">https://community.letsencrypt.org/t/certbot-0-21-0-release/50725</a></p>
  
  <p>but I tried apt-get update/upgrade and I get the following:</p>
  
  <pre><code>certbot is already the newest version.
  certbot set to manually installed.
  </code></pre>
  
  <p>Any suggestions on how to update?</p>