Create dependabot changelogs at release time (#15481)

* Ditch dependabot changelog workflow

* Summarise dependabot commits in release script

* Changelog

* Update scripts-dev/release.py

.github/workflows/dependabot_changelog.yml

@@ -1,49 +0,0 @@
-name: Write changelog for dependabot PR
-on:
-  pull_request:
-    types:
-      - opened
-      - reopened  # For debugging!
-
-permissions:
-  # Needed to be able to push the commit. See
-  #     https://docs.github.com/en/code-security/dependabot/working-with-dependabot/automating-dependabot-with-github-actions#enable-auto-merge-on-a-pull-request
-  # for a similar example
-  contents: write
-
-jobs:
-  add-changelog:
-    runs-on: 'ubuntu-latest'
-    if: ${{ github.actor == 'dependabot[bot]' }}
-    steps:
-      - uses: actions/checkout@v3
-        with:
-          ref: ${{ github.event.pull_request.head.ref }}
-      - name: Write, commit and push changelog
-        env:
-          PR_TITLE: ${{ github.event.pull_request.title }}
-          PR_NUMBER: ${{ github.event.pull_request.number }}
-        run: |
-          echo "${PR_TITLE}." > "changelog.d/${PR_NUMBER}".misc
-          git add changelog.d
-          git config user.email "github-actions[bot]@users.noreply.github.com"
-          git config user.name "GitHub Actions"
-          git commit -m "Changelog"
-          git push
-        shell: bash
-      # The `git push` above does not trigger CI on the dependabot PR.
-      #
-      # By default, workflows can't trigger other workflows when they're just using the
-      # default `GITHUB_TOKEN` access token. (This is intended to stop you from writing
-      # recursive workflow loops by accident, because that'll get very expensive very
-      # quickly.) Instead, you have to manually call out to another workflow, or else
-      # make your changes (i.e. the `git push` above) using a personal access token.
-      # See
-      # https://docs.github.com/en/actions/using-workflows/triggering-a-workflow#triggering-a-workflow-from-a-workflow
-      #
-      # I have tried and failed to find a way to trigger CI on the "merge ref" of the PR.
-      # See git commit history for previous attempts. If anyone desperately wants to try
-      # again in the future, make a matrix-bot account and use its access token to git push.
-
-  # THIS WORKFLOW HAS WRITE PERMISSIONS---do not add other jobs here unless they
-  # are sufficiently locked down to dependabot only as above.