Part cFS#1119, update action versions

[jphickey]

---

name: Workflows Change
about: Changes to files under .github/workflows/
labels: ci/workflows

Description of Change

Update cache action to v6

Linked Issue

Part of nasa/cFS#1119

Areas of Expertise Touched

• ASTRO
• CI/CD
• COSMOS
• Cybersecurity
• Docker
• EDS
• Git
• PSPs
• SBN
• SMP
• Tables
• TSN
• Unit Tests
• Other

---

Author Checklist

• Linked GitHub issue is referenced above
• Workflow changes were tested on a branch/fork before submitting this PR
• All workflows ran successfully on this branch

---

Reviewer Checklist

• Workflow logic is correct and achieves the stated goal
• Third-party actions are from trusted sources and pinned to a specific SHA/tag
• Secrets are handled appropriately (no secrets exposed in logs, least-privilege usage)
• Workflow permissions follow the principle of least privilege
• Changes do not break or bypass existing branch protection rules
• All workflow runs on this PR completed successfully
• Appropriate Expert areas have been reviewed

[arielswalker]

I double checked all workflows in this PR. Format check is throwing a warning but that is a reusable workflow that is fixed in an unmerged PR in cFS. I also noticed that the add-to-project workflow is throwing an unrelated warning On November 2, 2026, GitHub will restrict pull_request_target on public repositories by default. There should be an issue created to address this.