title: How to get commit date and time on GitLab CI
body: <p>Actually I have a need to get a timestamp of my commit in GitLab CI.
  Alredy have tested the official documentation of GitLab CI Variables here:
  <a href="https://docs.gitlab.com/ee/ci/variables" rel="noreferrer">https://docs.gitlab.com/ee/ci/variables</a></p>
  
  <p>But there are only commit variables for</p>
  
  <ul>
  <li>CI_COMMIT_SHA The commit revision for which project is built</li>
  <li>CI_COMMIT_TAG The commit tag name. Present only when building tags.</li>
  </ul>
  
  <p>Is there a way to achieve this? Need to add these values to variables. My prefered way would be to add it to the variables section.</p>
  
  <pre><code>job:
    variables:
      COMMIT_TIME: $(git_timestamp)
    script: echo $COMMIT_TIME
  </code></pre>
  
  <p>I'm open to any helpful suggestions.</p>