.github/workflows: allow redmine-upkeep to write comments

.github/workflows: allow redmine-upkeep to write comments

Fixes errors like:

    Posting a comment to GitHub PR #62992.
    GitHub API error posting comment to PR #62992: 401 Client Error: Unauthorized for url: https://api.github.com/repos/ceph/ceph/issues/62992/comments - Response: {"message":"Requires authentication","documentation_url":"https://docs.github.com/rest/issues/comments#create-an-issue-comment","status":"401"}

Signed-off-by: Patrick Donnelly <pdonnell@ibm.com>