Reset peter-evans/create-pull-request@v6 author

Commit 0918b9e updated to `peter-evans/create-pull-request@v6` and also
removed the `author` input. The v6 release changes the default values
for `author` and `committer`. The release notes say, "The default value
for `author` has been changed to `${{ github.actor }}`
`<${{ github.actor_id }}+${{ github.actor }}@users.noreply.github.com>`."
`github.actor` is actually the user who triggered the workflow run, not
the bot opening the PR.

This commit will add the `author` input back and will update the author
to match the default GitHub Actions bot user account used as `committer`
`github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>`.

https://github.com/peter-evans/create-pull-request/releases/tag/v6.0.0

.github/workflows/ci.yml

@@ -172,6 +172,7 @@ jobs:
           add-paths: |
             CHANGELOG.md
             docs/changelog.md
+          author: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
           branch: create-pull-request/${{ github.ref_name }}
           commit-message: Update changelog for version ${{ github.ref_name }}
           title: Update changelog for version ${{ github.ref_name }}