chore: fix failing markdown linting

[voxpelli]

Follow up to #5186 / #5189. The release-please changelog entry didn't conform with the markdown linting, lets exclude it (at least for now)

[github-actions]

PR Compliance Checks

Thank you for your Pull Request! We have run several checks on this pull request in order to make sure it's suitable for merging into this project. The results are listed in the following section.

Issue Reference

In order to be considered for merging, the pull request description must refer to a specific issue number. This is described in our Contributing Guide. We are closing this pull request for now but you can update the pull request description and reopen the pull request.
The check is looking for a phrase similar to: "Fixes #XYZ" or "Resolves #XYZ" where XYZ is the issue number that this PR is meant to address.

[DavidAnson]

@voxpelli, I'm curious why the project chose to turn off linting of CHANGELOG.md entirely instead of tweaking the 4 new * list item markers in #5189 to be consistent with the 451 existing - markers in that file? Has markdownlint let you down in some way?

(Edit to correct "listing"->"linting")

[voxpelli]

@DavidAnson Since those new items are generated by release-please and I wasn't sure if one could configure release-please to satisfy the linting

[DavidAnson]

Interesting. Sorry to bug folks. I use this repo as one of the backwards compatibility nightly tests for markdownlint, so I find out about violations pretty quickly. :)