Enable submodule checkout in GitHub Actions workflow

Author: Gioee

.github/workflows/main.yml

@@ -49,6 +49,8 @@ jobs:
     steps:
 
       - uses: actions/[email protected]
+        with:
+          submodules: true
 
       - name: build sqlite-ai
         run: make extension ${{ matrix.make && matrix.make || ''}}