enable submodule checkout in CI workflows

Co-authored-by: Copilot <copilot@github.com>

.github/workflows/pr-linux-cli-test.yml

@@ -17,6 +17,8 @@ jobs:
     steps:
       - name: Checkout microsoft/vscode
         uses: actions/checkout@v6
+        with:
+          submodules: true
 
       - name: Install Rust
         run: |