r-b summit 2023 hamburg: add group photo

  <li>Work together and hack on solutions.</li>

  <li>Discuss how reproducible builds will be usable and meaningful to users and developers alike.</li>

</ul>

<a href="/images/groupphoto_rb2023summit.jpg"><img style="margin-top: 10px; vertical-align: top;" src="{{ "/images/groupphoto_rb2023summit.jpg" | relative_url }}" alt="Reproducible Builds Summit 7 in Hamburg 2239"/></a>

<h2>Participants</h2>

<p>