Release notes: Use author if they are GitHub staff

[mbg]

Modifies update-release-branch.py to use the PR author if they are GitHub staff, or the merger as before otherwise.

Risk assessment

For internal use only. Please select the risk level of this change:

• Low risk: Changes are fully under feature flags, or have been fully tested and validated in pre-production environments and are highly observable, or are documentation or test only.

Which use cases does this change impact?

Environments:

• Testing/None - This change does not impact any CodeQL workflows in production.

How did/will you validate this change?

• None - I am not validating these changes.

If something goes wrong after this change is released, what are the mitigation and rollback strategies?

• Rollback - Change can only be disabled by rolling back the release or releasing a new version with a fix.

How will you know if something goes wrong after this change is released?

Release process will fail.

Are there any special considerations for merging or releasing this change?

• No special considerations - This change can be merged at any time.

Merge / deployment checklist

• Confirm this change is backwards compatible with existing workflows.
• Consider adding a changelog entry for this change.
• Confirm the readme and docs have been updated if necessary.

[Copilot]

Pull request overview

This PR updates the release-branch update automation to attribute merged PRs to the PR author when the author is GitHub staff, falling back to the merger otherwise. This affects the generated body text for release-related pull requests created by the workflow.

Changes:

• Adjust PR attribution in the generated PR body to prefer the PR author when site_admin is true.
• Add a helper (get_pr_author_if_staff) to encapsulate the staff-author selection logic.
• Remove a couple of trailing whitespace issues in replace_version_package_json.

Comments suppressed due to low confidence (1)

.github/update-release-branch.py:180

• get_pr_author_if_staff swallows all exceptions with a bare except Exception: pass, which can hide real failures (e.g., API/rate-limit issues) and make troubleshooting the release workflow harder. Consider either removing the try/except (since getattr(..., False) already handles missing attributes) or catching the specific expected exception type(s) and emitting a warning before falling back.

  try:
    if getattr(pr.user, 'site_admin', False):
      return pr.user.login
  except Exception:
    pass

[henrymercer]

I don't think this would throw if we're providing a default value, so I think we can remove the try/catch.