chore: sync workflow needs git-lfs (#31708)

i believe this is necessary as CDK requires git-lfs now.

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.github/workflows/sync-from-upstream.yml

@@ -43,15 +43,21 @@ jobs:
       contents: write
     needs: [check-secret]
     steps:
-      - name: Checkout using User Token
+      - name: Checkout using User Token (+ download lfs dependencies)
         if: needs.check-secret.outputs.ok == 'true'
         uses: actions/checkout@v4
         with:
+          lfs: true
           token: ${{ secrets.PROJEN_GITHUB_TOKEN }}
 
-      - name: Checkout using GitHub Actions permissions
+      - name: Checkout using GitHub Actions permissions (+ download lfs dependencies)
         if: needs.check-secret.outputs.ok == 'false'
         uses: actions/checkout@v4
+        with:
+          lfs: true
+
+      - name: Checkout LFS objects
+        run: git lfs checkout
 
       - name: Sync from aws/aws-cdk
         run: |-