[Automated] Update backstage-plugins-eventing nightly (#394)

Update eventing nightly

bumping knative.dev/eventing 59b517c...71a6c9f:
  > 71a6c9f fix: EventTransform not updating when expression changes (# 8848)
  > 45c284b [main] Upgrade to latest dependencies (# 8847)

Signed-off-by: Knative Automation <automation@knative.team>

Author: knative-automation