Add `channel` to trigger inputs

[zimeg]

Type of change

• [ ] New sample
• [ ] New feature
• [x] Bug fix
• [ ] Documentation

Summary

This PR adds a channel input with a channel_id value to the trigger for sample_workflow to include all necessary inputs for this workflow. Closes #30.

Requirements

• [x] I’ve checked my submission against the Samples Checklist to ensure it complies with all standards
• [x] I have ensured the changes I am contributing align with existing patterns and have tested and linted my code
• [x] I've read and agree to the Code of Conduct