chore: migrate remaining workflow github-script steps to v8

[accesswatch]

Summary

• upgrade remaining actions/github-script workflow usages from v7 to v8
• apply updates in day2-release, registration, learning-room-validation, skills-progression, and student-grouping workflows

Why

GitHub Actions runners are deprecating Node 20 for JavaScript actions. Upgrading to v8 aligns these workflows with Node 24 support.

Validation

• searched target workflows to confirm no remaining actions/github-script@v7 references

[github-actions]

Peer Review Assigned

Hi @accesswatch! Your PR has been automatically paired with @taylorarndt for peer review.

For @taylorarndt:

This is a great opportunity to practice code review skills! Here's what to look for:

Content Quality:

• Does the change accomplish what the issue describes?
• Is the writing clear and helpful?
• Are there any typos or grammar issues?

Accessibility:

• Proper heading hierarchy (H1 → H2 → H3, no skips)?
• Descriptive link text (not "click here")?
• Alt text on images?
• [TODO] markers removed?

Documentation:

• Code blocks are properly formatted?
• Tables have headers?
• References/links work correctly?

Review Guidelines:

• Be kind and constructive
• Suggest improvements, don't just point out problems
• Ask questions if something is unclear
• Approve when ready or request changes with explanation

Resources:

• How to Review PRs
• Writing Good Review Comments

---

Pairing by Learning Room Grouping Engine