support passing secrets to gha-puppet workflow

[h-haaks]

This PR is related to voxpupuli/gha-puppet#108

My intention is to have something like this in modules .sync.yml

.github/workflows/ci.yml:
  with:
    upstream_repo_auth_id: ${{ vars.REPO_AUTH_ID }}
  secrets:
    upstream_repo_auth_secret: ${{ secrets.REPO_AUTH_SECRET }}

where vars.REPO_AUTH_ID and secrets.REPO_AUTH_SECRET are GitHub repo/organization variable/secret.