[Automated] Update backstage-plugins-eventing nightly (#87)

Update eventing nightly

bumping knative.dev/eventing 608e76c...1708881:
  > 1708881 [main] Upgrade to latest dependencies (# 8191)
  > b48b664 feat: add constructor for full event lineage graph (# 7921)
  > e79f3b6 Make auth package indepent from eventpolicy informer (# 8195)
  > ae6ed99 Fix JobSink to support AuthZ on GET too (# 8196)

Signed-off-by: Knative Automation <[email protected]>