my update.yml:

  name: Update Website
  on:
    push:
      branches:
      - production
  jobs:
    deploy:
      runs-on: ubuntu-latest
      steps:
      - uses: actions/checkout@master
      - uses: jakejarvis/s3-sync-action@master
        with:
          args: 
        env:
          AWS_S3_BUCKET: ${{ secrets.AWS_S3_BUCKET }}
          AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }}
          AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
          AWS_REGION: 'myregion'
          SOURCE_DIR: 'mydir'