Fix issue-triage workflow to add labels via add-labels safe-output (g…

…ithub#6)

* Initial plan

* Add add-labels safe-output to issue-triage workflow

Co-authored-by: friggeri <106686+friggeri@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: friggeri <106686+friggeri@users.noreply.github.com>