pr_6553.prdoc

title: Ensure sync event is processed on unknown peer roles

doc:
  - audience: Node Dev
    description: |
      The GossipEngine::poll_next implementation polls both the notification_service and the sync_event_stream.
      This PR ensures both events are processed gracefully.

crates:
  - name: sc-network-gossip
    bump: patch
  - name: sc-network-sync
    bump: patch