github_action_base64_example.yml

name: Deploy Dev

on:
  workflow_run:
    workflows: ["CI"]
    types:
      - completed
    branches:
      - develop
job:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - name: Build ENV
        run: echo "${{ secrets.BACKEND_ENV }}" | base64 -d > .env
      - name: Deploy
        run: ...