feat(cert-manager): upgrade to v1.20.2 and enable Gateway API support

- Upgrade chart from v1.19.2 to v1.20.2
- Enable enableGatewayAPI via ControllerConfiguration config block
  so cert-manager watches Gateway resources and issues certs from
  cert-manager.io/* annotations (required for consul/vault Gateway certs)

apps/overlays/au-syd1/cert-manager/kustomization.yaml

@@ -8,7 +8,7 @@ resources:
 helmCharts:
   - name: cert-manager
     repo: https://artifactapi.k8s.syd1.au.unkin.net/api/v1/virtual/helm
-    version: "v1.19.2"
+    version: "v1.20.2"
     releaseName: cert-manager
     namespace: cert-manager
     valuesFile: values.yaml

apps/overlays/au-syd1/cert-manager/values.yaml

@@ -1,6 +1,11 @@
 crds:
   enabled: true
 
+config:
+  apiVersion: controller.config.cert-manager.io/v1alpha1
+  kind: ControllerConfiguration
+  enableGatewayAPI: true
+
 replicaCount: 2
 
 resources: