test(deps): update actions/setup-node to v6

[MikeMcC399]

• closes Update actions/setup-node to node24 version #1562
• supports resolution of Update action to run under Node.js 24 #1519

Situation

Workflows and examples currently use the GitHub Actions actions/setup-node version v4 with runs.using: node20.

GitHub has deprecated the use of node20 and will force runners to use node24 beginning on Mar 4, 2026 - see Deprecation of Node 20 on GitHub Actions runners.

Change

• Update all usage of actions/setup-node in examples and documentation to v6 with runs.using: node24.

• Harmonize the step name across examples to "Install Node.js"

• Change example usage of node-version: 22 to node-version: 24 where used in text

[cypress-app-bot]

• Create a Draft Pull Request if your PR is not ready for review. Mark the PR as Ready for Review when you're ready for a Cypress team member to review the PR.

[MikeMcC399]

Note: After this PR is merged, I would plan to submit a PR to update the cypress-io/github-action to node24. The update to actions/setup-node is the last gating item, and it has been waiting for some time for the GitHub Actions team to progress with resolving their cache issues.

[jennifer-shehane]

Thank you! 🙏🏻

[MikeMcC399]

@jennifer-shehane

You've approved without yet merging. Would you like to now merge so that I can progress with other PRs?