Fix CI

.github/workflows/ci-server.yaml

@@ -9,8 +9,13 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
+        if: github.head_ref == 'main'
         with:
           ref: ${{ github.head_ref || github.ref_name }}
+      - uses: actions/checkout@v3
+        if: github.head_ref != 'main'
+        with:
+          ref: "refs/pull/${{ github.event.number }}/merge"
       - name: Setup Node.js
         uses: actions/setup-node@v3
         with: