Run conformance tests on minimum k8s version

[ciarams87]

Proposed changes

As a developer
I would like the conformance tests to run on both the latest and minimum supported kubernetes versions
So that I can have confidence that my changes work on all k8s versions we currently support

Solution:
Create a matrix for conformance tests to run both the latest and minimum supported kubernetes versions.

Note: The minimum required version of k8s is 1.23 not 1.22. The Gateway APIs cannot be installed into 1.22:

kubectl apply -f https://github.com/kubernetes-sigs/gateway-api/releases/download/v0.8.0/standard-install.yaml

error: error validating "https://github.com/kubernetes-sigs/gateway-api/releases/download/v0.8.0/standard-install.yaml": error validating data: [ValidationError(CustomResourceDefinition.spec.versions[0].schema.openAPIV3Schema.properties.spec.properties.controllerName): unknown field "x-kubernetes-validations" in io.k8s.apiextensions-apiserver.pkg.apis.apiextensions.v1.JSONSchemaProps, ValidationError(CustomResourceDefinition.spec.versions[1].schema.openAPIV3Schema.properties.spec.properties.controllerName): unknown field "x-kubernetes-validations" in io.k8s.apiextensions-apiserver.pkg.apis.apiextensions.v1.JSONSchemaProps]; if you choose to ignore these errors, turn validation off with --validate=false

See https://github.com/kubernetes-sigs/gateway-api/releases

Closes #937

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork