title: Remote Rejects Push With Commit Must Have Valid Signature
body: <p>I am getting this error when doing a push</p>
  <pre class="lang-sh prettyprint-override"><code>git push
  Enumerating objects: 13, done.
  Counting objects: 100% (13/13), done.
  Delta compression using up to 8 threads
  Compressing objects: 100% (7/7), done.
  Writing objects: 100% (7/7), 586 bytes | 195.00 KiB/s, done.
  Total 7 (delta 6), reused 0 (delta 0)
  remote: Resolving deltas: 100% (6/6), completed with 6 local objects.
  remote: error: GH006: Protected branch update failed for refs/heads/master.
  remote: error: Commits must have valid signatures.
  To https://github.com/xxx-xxx-xxx
   ! [remote rejected]   master -&gt; master (protected branch hook declined)
  error: failed to push some refs to 'https://github.com/xxx-xxx-xxx'
  </code></pre>
  <p>How do I fix this?</p>