Keep GitHub Actions up to date with GitHub's Dependabot

[cclauss]

Dependabot will generate a pull request like rapidfuzz/RapidFuzz#362 to keep the six GitHub Actions used in .github/workflows/test.yml up-to-date.

• https://docs.github.com/en/code-security/dependabot/working-with-dependabot/keeping-your-actions-up-to-date-with-dependabot
• https://docs.github.com/en/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file#package-ecosystem

Failing docs tests are fixed in:

• 631

• 633

[cclauss]

This will fix 30 of the warnings at the bottom right of https://github.com/pytest-dev/pytest-cov/actions/runs/8193686290

Node.js 16 actions are deprecated...