Update net-istio nightly (#12252)
Update net-istio nightly (#12252)

bumping knative.dev/net-istio 158821d...89e78c4:
  > 89e78c4 Update actions (# 806)
  > 1634a28 upgrade to latest dependencies (# 807)
  > 6bb9f29 upgrade to latest dependencies (# 805)
  > c67a7d6 Revert "Use GKE 1.20 (# 781)" (# 791)

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