Update supported OCP versions for ECK 3.2 (#4011)

We retested ECK with 4.20 and want to update the officially supported
version.

Author: pebrc

deploy-manage/deploy/cloud-on-k8s.md

@@ -77,7 +77,7 @@ ECK is compatible with the following Kubernetes distributions and related techno
 
 :::{tab-item} ECK 3.2
 * Kubernetes 1.30-1.34
-* OpenShift 4.15-4.19
+* OpenShift 4.15-4.20
 * Google Kubernetes Engine (GKE), Azure Kubernetes Service (AKS), and Amazon Elastic Kubernetes Service (EKS)
 * Helm: {{eck_helm_minimum_version}}+
 :::