ci: try to fix commit-pr workflow

Signed-off-by: Ettore Di Giacinto <mudler@users.noreply.github.com>

.github/workflows/comment-pr.yaml

@@ -8,9 +8,10 @@ jobs:
         MODEL_NAME: hermes-2-theta-llama-3-8b
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
+    - name: Checkout code
+      uses: actions/checkout@v3
       with:
-        fetch-depth: 0 # needed to checkout all branches for this Action to work
+        ref: "${{ github.event.pull_request.merge_commit_sha }}"
     - uses: mudler/localai-github-action@v1
       with:
         model: 'hermes-2-theta-llama-3-8b' # Any from models.localai.io, or from huggingface.com with: "huggingface://<repository>/file"