inputs: fix typo in steering_ctx kwargs

[diegodelemos]

• (Closes yadage: read workflow inputs from canonical location #38).

[diegodelemos]

In order to use input files with yadage the filenames should be passed as arguments i.e.:

For the given workflow:

stages:
  - name: hello_world
    dependencies: ['init']
    scheduler:
      scheduler_type: singlestep-stage
      parameters:
        outputfile: '{workdir}/hello_world.txt'
        # Add the inputfile parameter to the worklfow spec.
        inputfile: {stages: init, output: inputfile, unwrap: true})
      step:
        process:
          process_type: 'string-interpolated-cmd'
          cmd: 'cat {inputfile} > {outputfile}'
        publisher:
          publisher_type: 'frompar-pub'
          outputmap:
            outputfile: outputfile
        environment:
          environment_type: 'docker-encapsulated'
          image: busybox

So before starting it, we should provide {'inputfile': 'input.txt'} as a workflow parameter apart from seeding it (reana-client inputs upload input.txt --workflow mega-workflow).

⚠️ In yadage 0.12.13 it is yadage.utils.discover_initfiles who takes care of resolving input files path. Remember that the fact that we are using a shared volume and the same base path allows this feature to work meaning that: the path gets resolved in the workflow-engine file system which for /data happens to be the same both in workflow-engine and job container (see job-controller mount_path and storage_paths and workflow-engine mount path and storage path).