CI Fix Assign workflow (scikit-learn#29408)

Author: lesteve

.github/workflows/assign.yml

@@ -19,8 +19,11 @@ jobs:
        && !github.event.issue.assignee
     steps:
       - run: |
+          # Using REST API directly because assigning through gh has some severe limitations. For more details, see
+          # https://github.com/scikit-learn/scikit-learn/issues/29395#issuecomment-2206776963
           echo "Assigning issue ${{ github.event.issue.number }} to ${{ github.event.comment.user.login }}"
-          gh issue edit $ISSUE --add-assignee ${{ github.event.comment.user.login }}
+          curl -H "Authorization: token $GH_TOKEN" -d '{"assignees": ["${{ github.event.comment.user.login }}"]}' \
+              https://api.github.com/repos/${{ github.repository }}/issues/${{ github.event.issue.number }}/assignees
           gh issue edit $ISSUE --remove-label "help wanted"
         env:
           GH_TOKEN: ${{ github.token }}