Update net-istio nightly (#12626)
Update net-istio nightly (#12626)

bumping knative.dev/net-istio 9efdcb8...3e34f56:
  > 3e34f56 upgrade to latest dependencies (# 872)
  > 9e22e8c updates val webhook selector for more granularity (# 868)

Signed-off-by: Knative Automation <f415700d4d0ce1c81810fe7553e3eea2bed16231@knative.team>
knative/serving,knative/serving