Support setting env variables in GH action

[arnauorriols]

Integrate with GH secrets?

[csvn]

This would be very helpful! I'm not sure what you mean by "Integrate with GH secrets", but if there was an input that could handle a pre-defined syntax for secrets, it would be easy to include manually, right?

      - uses: denoland/deployctl@v1
        with:
          env: |
            SHA=${{ github.sha }}
            MY_SECRET=${{ secrets.MY_SECRET }}

I was hoping to include some metadata from the current build as environment variables to the deploy, and it would be nice if this could be achieved with the action, and not just with deployctl deploy.