Locked Dependencies for GitHub Actions Workflows [GA]

### Value Prop
With workflow-embedded dependency locking in GitHub Actions, you can ensure your CI/CD pipelines always use the exact versions of Actions and dependencies you’ve reviewed. This gives you reproducible builds, clear visibility into changes, and stronger protection against unexpected or compromised code.

### Expected Outcome
By making dependency resolution explicit and verifiable, this feature helps teams prevent silent drift and supply chain risks in their workflows. The goal is to improve reliability, security, and confidence in every workflow run, so you can focus on building and shipping with peace of mind.