Keep GitHub Actions up to date with GitHub's Dependabot

[cclauss]

Fixes software supply chain safety warnings like at the bottom right of
https://github.com/OCamlPro/gnucobol/actions/runs/11480929540

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

[GitMensch]

conceptional looks good to me

questions:

1. Which branches are monitored / PRs created for (I guess the configured main branch)?
2. How do dependabot PRs look like? I guess that you may be able to trigger that workflow as soon as you change the main branch in your GH project settings to patch-1 or push that to your current one.

[cclauss]

Dependabot monitors the default branch of the repo and PRs look like:

• Bump the github-actions group with 2 updates nateshmbhat/pyttsx3#344
• Bump the github-actions group with 3 updates btsimonh/node-ffi-napi#3

[GitMensch]

please adjust the default branch of your fork, this way we'll see one of the resulting PRs in your repo

[cclauss]

https://github.com/cclauss/gnucobol/blob/gcos4gnucobol-3.x/.github/dependabot.yml

[cclauss]

https://github.com/cclauss/gnucobol/actions/runs/11503260118