Add checkout, python setup steps for approval workflow

.github/workflows/approve-label.yml

@@ -73,6 +73,17 @@ jobs:
     if: contains(github.event.label.name, 'approved')
     runs-on: ubuntu-latest
     steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      # setup python
+      - name: setup python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.10"
+          cache: "pip"
+      - run: pip install -r requirements.txt
+
       - name: Verify Labeler
         id: verify_labeler
         env: