Keep GitHub Actions up to date with GitHub's Dependabot

[cclauss]

Automates the creation of pull requests like

• 1458

Fixes software supply chain safety warnings like at the bottom right of https://github.com/openstax/openstax-cms/actions/runs/11408898861

• Keeping your actions up to date with Dependabot
• Configuration options for the dependabot.yml file - package-ecosystem

[cclauss]

Generated:

• 1595