[Automated] Update backstage-plugins-eventing nightly (#149)

Update eventing nightly

bumping knative.dev/eventing f3ea6b5...9cec50f:
  > 9cec50f [main] Upgrade to latest dependencies (# 8414)
  > a40a0a7 [main] Upgrade to latest dependencies (# 8413)
  > 90edfe6 Upgrade deps to latest (# 8410)
  > 6d71005 Additional unit tests for EventPolicy (# 8405)

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

Author: knative-automation