Allow unsafe PR checkout in CI documentation workflow

Author: eseiler

.github/workflows/ci_documentation.yml

@@ -42,6 +42,7 @@ jobs:
         uses: actions/checkout@v7
         with:
           ref: "refs/pull/${{ github.event.number }}/merge"
+          allow-unsafe-pr-checkout: true
 
       - name: Install Doxygen
         uses: seqan/actions/setup-doxygen@main