ci: Update actions

[joeyparrish]

This silences warnings about outdated node runtimes in CI jobs.

• Trivial upgrades:
  • actions/checkout@v3 => v4
  • actions/deploy-pages@v2 => v4
  • actions/upload-pages-artifact@v2 => v3
  • mxschmitt/action-tmate@v3.6 => v3.17
  • mikepenz/action-junit-report@v3.8.0 => v4
• Upgrades that required small changes or deeper testing:
  • actions/download-artifact@v3 => v4
  • actions/upload-artifact@v3 => v4
  • google-github-actions/release-please-action@v3 => v4
• Replaced:
  • svenstaro/upload-release-action@v2 => gh CLI

See also:

• https://github.com/actions/upload-artifact/blob/main/docs/MIGRATION.md

[joeyparrish]

Fully tested with a fake release on my fork.