CHIPFLOW_BACKEND_VERSION to submit test

Author: mooperd

.github/workflows/main.yaml

@@ -74,6 +74,7 @@ jobs:
           pdm run chipflow pin lock
           pdm run chipflow silicon submit
         env:
+          CHIPFLOW_BACKEND_VERSION: b7afdbf
           CHIPFLOW_API_ORIGIN: 'https://build-staging.chipflow.org'
           CHIPFLOW_API_KEY_ID: ${{ secrets.CHIPFLOW_API_KEY_ID }}
           CHIPFLOW_API_KEY_SECRET: ${{ secrets.CHIPFLOW_API_KEY_SECRET }}