Update net-kourier nightly (#11807)
Update net-kourier nightly (#11807)

bumping knative.dev/net-kourier b6929c8...a20e6f4:
  > a20e6f4 Update community files (# 594)

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