Adapt the checkout configuration, to match the expectations of EndBug/add-and-commit@v9

Author: spier

.github/workflows/generate-mindmap.yml

@@ -36,6 +36,9 @@ jobs:
 
     steps:
     - uses: actions/checkout@v5
+      with:
+        repository: ${{ github.event.pull_request.head.repo.full_name }}
+        ref: ${{ github.event.pull_request.head.ref }}
     - name: Use Node.js
       uses: actions/setup-node@v5
       with: