Update Managed Kubernetes version for e2e tests (#413)

OKE no longer supports anything below v1.30.x. It was causing the
managed e2e tests to fail.

Author: joekr

test/e2e/config/e2e_conf.yaml

@@ -83,8 +83,8 @@ providers:
 
 variables:
   KUBERNETES_VERSION: "v1.29.6"
-  OCI_MANAGED_KUBERNETES_VERSION: "v1.28.2"
-  OCI_MANAGED_KUBERNETES_VERSION_UPGRADE: "v1.29.1"
+  OCI_MANAGED_KUBERNETES_VERSION: "v1.31.1"
+  OCI_MANAGED_KUBERNETES_VERSION_UPGRADE: "v1.32.1"
   EXP_CLUSTER_RESOURCE_SET: "true"
   NODE_DRAIN_TIMEOUT: "60s"
   CI_VERSION: ""