ci: also checkout submodules

Author: haoqunjiang

.github/workflows/ci.yml

@@ -30,7 +30,9 @@ jobs:
             os: ubuntu-latest
     name: Node ${{ matrix.node-version }} on ${{ matrix.os }}
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v2
+        with:
+          submodules: 'recursive'
       - uses: pnpm/[email protected]
         with:
           version: 6