Locked Dependencies for GitHub Actions Workflows [Public Preview]

### Value Prop
You can now lock the exact versions of all actions and their dependencies directly in your workflow files. This gives you clear visibility into what code is running in your CI/CD pipelines, helps you catch changes before they happen, and ensures every workflow run is consistent and secure.

### Expected Outcome
By making dependencies explicit and verifiable, teams can trust that workflows will run the same way every time, with no surprises from hidden updates or transitive changes. This approach boosts reliability, makes reviews easier, and strengthens supply chain security for your automation at scale.