message: Update constitution reference in open-source page
diff: <img id="open-source-humaaan" class="top-left-humaaan" style="margin-top: -70px;" src="/img/humaaans/open-source.svg">
  -Open Source is at the very core of datarequests.org. We have designed the project from the ground up to be as open as possible. Our [constitution](https://www.datarequests.org/verein/constitution/) requires us to publish our content under free licenses.
  +Open Source is at the very core of datarequests.org. We have designed the project from the ground up to be as open as possible. Our [constitution]({{< ref "verein/constitution" >}}) requires us to publish our content under free licenses.
  We are huge proponents of Open Source and believe in it.
  