error when following quickstart guide

[nirrozenbaum]

as part of PR #450 some changes were made to config/manifests/gateway/extension_policy.yaml. after the last change I wasn't able to deploy the resource.

nirro$ kubectl apply -f https://github.com/kubernetes-sigs/gateway-api-inference-extension/raw/main/config/manifests/gateway/extension_policy.yaml
Error from server (BadRequest): error when creating "https://github.com/kubernetes-sigs/gateway-api-inference-
extension/raw/main/config/manifests/gateway/extension_policy.yaml": EnvoyExtensionPolicy in version "v1alpha1" 
cannot be handled as a EnvoyExtensionPolicy: strict decoding error: unknown field 
"spec.extProc[0].processingMode.allowModeOverride"

cc @kfswain

[kfswain]

Ack. Are you on envoy 1.2, we may need to up our requirement to 1.3

[nirrozenbaum]

indeed. I just tested it using several versions. in 1.2.7 (which is latest 1.2) it fails. in 1.3.0 it runs successfully.
pushing a fix.