[actions] checkout repo before labels edit

Author: capcom6

.github/workflows/pr-labels.yml

@@ -10,6 +10,11 @@ jobs:
     permissions:
       pull-requests: write # Grant permission to modify labels
     steps:
+      # step 1: checkout repository code
+      - name: Checkout code into workspace directory
+        uses: actions/checkout@v4
+
+      # step 2: remove specific labels
       - name: Remove specific labels
         run: gh pr edit ${{ github.event.pull_request.number }} --remove-label "ready,deployed"
         env: