Implement support for digest updates

[JustArchi]

Closes #25

I've tested this to work with the very simple git submodules repo and following config:

name: ASF-auto-merge

on:
  pull_request_target:

jobs:
  auto-merge:
    if: github.actor == 'dependabot[bot]'
    runs-on: ubuntu-latest
    steps:
      - name: Auto-merge PR if deemed appropriate
        uses: JustArchi/action-dependabot-auto-merge@issue-25
        with:
          github-token: ${{ secrets.PERSONAL_TEST }}
          target: digest

You might want to squash my mess of test commits to get this in order, but apart from messy history, it looks good to me. I've tried to make it as reliable as possible, so the regex is actually looking for abcdef1234567890 in block quotes, since dependabot seems to use them for digest updates. I don't believe we can catch anything else by accident, see: https://github.com/JustArchi/auto-merge-tests/pull/1

Thank you in advance for considering this enhancement, feel free to edit my branch if you'd like to.

[JustArchi]

I've cleaned up the mess, should be good to go now, squashed or not 🙂

[ahmadnassri]

sorry for the delay, can you please resolve the conflict, and update the README ?

[JustArchi]

Sorry, I'm no longer using dependabot as I moved to renovate several months ago and as I'm pretty busy as of now and I have no intention of ever coming back to it as inferior alternative (neither test it), I'm no longer interested in keeping this PR up either.

Feel free to adapt changes in this PR if you still consider it appropriate and wanted in your project, as of me I'm closing the request to merge it. Feel free to close my linked issue as well if you no longer find it justified after my resignation from being interested in it (although it probably would still benefit other people if it happened).

[ahmadnassri]

no worries and thank you.