Add required-fields to changelog.d config (backport #9810)

[mergify]

See https://codeberg.org/fgaz/changelog-d/issues/6

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Template Β: This PR does not modify cabal behaviour (documentation, tests, refactoring, etc.)

Include the following checklist in your PR:

• Patches conform to the coding conventions.
• Is this a PR that fixes CI? If so, it will need to be backported to older cabal release branches (ask maintainers for directions).

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This is an automatic backport of pull request #9810 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 5168b01 has failed:

On branch mergify/bp/3.12/pr-9810
Your branch is ahead of 'origin/3.12' by 1 commit.
  (use "git push" to publish your local commits)

You are currently cherry-picking commit 5168b01c1.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   changelog.d/config

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   changelog.d/issue-8680
	deleted by us:   changelog.d/issue-9098-lexbraces
	deleted by us:   changelog.d/issue-9678
	deleted by us:   changelog.d/issue-9736
	deleted by us:   changelog.d/pkgconfig-once

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[ulysses4ever]

@mergify rebase

[mergify]

rebase

✅ Nothing to do for rebase action