use qemu for iso stage

.github/workflows/startos-iso.yaml

@@ -221,6 +221,9 @@ jobs:
           sudo rm -rf "$AGENT_TOOLSDIRECTORY"    # Pre-cached tool cache (Go, Node, etc.)
         if: ${{ github.event.inputs.runner != 'fast' }}
 
+      - name: Set up docker QEMU
+        uses: docker/setup-qemu-action@v3
+
       - uses: actions/checkout@v4
         with:
           submodules: recursive