at the moment we compile a script that we can pipe in as single command
this is because of the constrains the docker backend gives us.
so we move it into the docker backend and eventually get rid of it altogether
Dropped support for `DRONE_*` environment variables in pipeline steps. Pipeline meta-data can be accessed with `CI_*` variables.
- `CI_*` prefix replaces `DRONE_*`
- `CI` value is now `woodpecker`
- `DRONE=true` has been removed
