Add git cliff toml to support generation of changelog (backport #2697)

[mergify]

This is an automatic backport of pull request #2697 done by Mergify.
Cherry-pick of 3e072a1 has failed:

On branch mergify/bp/release/v2.5.x/pr-2697
Your branch is up to date with 'origin/release/v2.5.x'.

You are currently cherry-picking commit 3e072a1.
  (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:   .github/PULL_REQUEST_TEMPLATE.md
	modified:   CHANGELOG.md
	modified:   CONTRIBUTING.md
	new file:   cliff.toml

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   Makefile

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

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