OZG-6477 OZG-7299 Fix white bg color in dark mode

alfa-client/libs/collaboration/src/lib/collaboration-in-vorgang-container/collaboration-list-container/collaboration-request/collaboration-request.component.html

-<div class="block bg-white p-4 m-2 mt-4" role="region" aria-labelledby="collaboration-title">
+<div class="m-2 mt-4 block bg-whitetext p-4" role="region" aria-labelledby="collaboration-title">
   <h2 id="collaboration-title" class="mb-4 text-xl text-text">
     <span class="font-semibold">{{ collaboration.titel }}</span>
   </h2>