ci: automate changelog from PR names

[shamykyzer]

• Add Changelog CI workflow for release PRs
• Reformat generated changelog to match existing style (version date, bullet format)
• Add changelog-ci config and reformat script
• Update CONTRIBUTING: changelog auto-generated, document release workflow

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.77%. Comparing base (f258e9a) to head (44174ea).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #352   +/-   ##
=======================================
  Coverage   99.77%   99.77%           
=======================================
  Files           9        9           
  Lines        1314     1314           
=======================================
  Hits         1311     1311           
  Misses          3        3           

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[shamykyzer]

Hello @rpreen , i looked into it and Commitizen didn’t feel like the right fit here because it’s commit based and mainly release time focused.

Since we want PR title based entries, i went with Changelog CI plus a small reformatter as it matched the repo policy and will keep the versioning and the release process unchanged.

Also I couldn't continue this development further due to the bot not having write permissions I think.

Let me know what you think and where I can go from here. 👍🏼

[rpreen]

I think this is a more complicated solution than we need. If I understand correctly, any time someone opens a PR the bot will push a new commit onto their branch, which they will probably not expect or appreciate. Their local branch will then be behind, so they will have to do a pull before they can make any further commits. If multiple PRs are opened simultaneously both will modify the changelog in the same location causing a merge conflict.

I think for us we need a simpler solution that only runs before a release - I just added a comment on #327 about this.