Pin GitHub Actions to full-length commit SHAs

[OssSecurityBot]

Summary

This PR pins GitHub Actions to full-length commit SHAs for improved security and reproducibility and adds a 7 day cooldown to Dependabot configuration for GitHub Actions.

Why?

Pinning actions to commit SHAs prevents supply-chain attacks where a tag could be moved to point to malicious code. This is a recommended security best practice per the GitHub Actions security hardening guide.

This change mitigates the risk of tag retargeting to malicious code as seen in incidents like the tj-actions/changed-files action compromise or codfish/semantic-release-action compromise and improves the integrity and reproducibility of the CI/CD pipeline.

What changed?

Action pinning: Third-party action references in .github/workflows/ that used mutable tag-based references (e.g., actions/checkout@v4) have been updated to full-length commit SHAs with a version comment (e.g., actions/checkout@<sha> # v4) using the pinact tool. References that were already pinned to a SHA, or that used immutable release tags, were left unchanged.

Dependabot configuration: .github/dependabot.yml has been updated to ensure a github-actions package-ecosystem section is present with a cooldown configuration (default-days: 7). This groups Dependabot PRs for GitHub Actions and enforces a minimum 7-day cooldown between updates. If the file did not exist, it was created. If a github-actions section already existed, only the cooldown block was added or its default-days value was increased to 7 if it was lower. The 7-day cooldown provides a window for the community to detect and report compromised releases before they are automatically proposed as updates, reducing exposure to supply-chain attacks via newly published malicious versions.

Is this safe to merge?

Yes. The pinned SHAs correspond to the same commits that the existing tags pointed to. No behavioral changes are introduced. You can verify the pinned SHA value using the GitHub REST API (e.g., the commit hash for actions/checkout@v7 can be found in the sha property in the JSON response for GET https://api.github.com/repos/actions/checkout/commits/v7).

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_{For more information, visit https://aka.ms/action-pinning}

[Copilot]

Pull request overview

This PR hardens the repository’s CI/CD supply chain by replacing mutable GitHub Actions references with full-length commit SHAs (for reproducibility and reduced tag-retargeting risk) and introduces Dependabot configuration for GitHub Actions with a 7‑day cooldown.

Changes:

• Pinned multiple third-party GitHub Actions in workflow files to full commit SHAs with version comments.
• Added a new .github/dependabot.yml configuration to update github-actions weekly, grouped, with a 7-day cooldown.

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
.github/workflows/wiki-sync.yml	Pins actions/checkout to a full SHA for the wiki sync workflow.
.github/workflows/update-mslearn-dates.yml	Pins actions/checkout and tj-actions/changed-files to SHAs for mslearn date updates.
.github/workflows/publish.yml	Pins psmodulecache and actions/checkout to SHAs for the publish workflow.
.github/workflows/opendata-commitment-eligibility.yml	Pins actions/checkout to a SHA for the scheduled eligibility update.
.github/workflows/opendata-ci.yml	Pins actions/checkout and actions/github-script to SHAs for open data CI.
.github/workflows/ftk-pr-deploy.yml	Pins actions/cache, actions/checkout, and azure/login to SHAs across PR deploy jobs.
.github/workflows/ftk-pr-cleanup.yml	Pins azure/login to a SHA for PR cleanup.
.github/workflows/dev.yml	Pins psmodulecache and actions/checkout to SHAs for PowerShell tests.
.github/workflows/aoe-cd-test.yml	Pins actions/checkout to a SHA in AOE CD test workflow.
.github/workflows/aoe-cd-prod.yml	Pins actions/checkout to a SHA in AOE CD prod workflow.
.github/workflows/aoe-cd-dev.yml	Pins actions/checkout to a SHA in AOE CD dev workflow.
.github/workflows/accessibility-alt-text.yml	Pins github/accessibility-alt-text-bot to a SHA.
.github/dependabot.yml	Adds Dependabot updates for github-actions with grouping and a 7-day cooldown.