fix: passing secret as sensitive config

[rangoo94]

Pull request description

kind: TestWorkflow
apiVersion: testworkflows.testkube.io/v1
metadata:
  name: example-workflow
spec:
  steps:
  - name: Run tests
    template:
      name: example-template
      config:
        something: '{{ secret("some-secret", "key") }}'
---
kind: TestWorkflowTemplate
apiVersion: testworkflows.testkube.io/v1
metadata:
  name: example-template
spec:
  config:
    something:
      type: string
      sensitive: true
  steps:
  - shell: echo {{ config.something }}

Checklist (choose whats happened)

• breaking change! (describe)
• tested locally
• tested on cluster
• added new dependencies
• updated the docs
• added a test