add CI Checkout code

.gitea/workflows/ci.yml

@@ -12,6 +12,10 @@ jobs:
     runs-on: act_runner_java
     if: ${{ github.event.pull_request.merged == true }}
     steps:
+      - name: Checkout code
+        run: |
+          git clone ${{ github.server_url }}/${{ github.repository }}.git .
+          git checkout ${{ github.sha }}
       - name: Set up environment
         run: |
           echo "PR #${{ github.event.number }} merged into master"