https://github.com/knative/docs/blob/release-0.13/docs/install/installing-istio.md

[PhilCorney]

GitHub URL 404s for the the below Istio version

Istio minor version should be 1.3, 1.4 or 1.5

export ISTIO_MINOR_VERSION=1.3

export VERSION=$(curl https://raw.githubusercontent.com/knative/serving/master/third_party/istio-${ISTIO_MINOR_VERSION}-latest)

kubectl apply -f https://raw.githubusercontent.com/knative/serving/master/third_party/${VERSION}/istio-knative-extras.yaml

[sebgoa]

indeed, 1.3 was removed here knative/serving@0762cfc#diff-15230e5dad94ffaefa7b526c0c1e89e5