update to how latest gke master version is fetched

Author: danisla

example-gke-k8s-helm/main.tf

@@ -37,7 +37,7 @@ resource "google_container_cluster" "default" {
   name               = "tf-gke-helm"
   zone               = "${var.zone}"
   initial_node_count = 3
-  min_master_version = "${data.google_container_engine_versions.default.latest_node_version}"
+  min_master_version = "${data.google_container_engine_versions.default.latest_master_version}"
   network            = "${google_compute_subnetwork.default.name}"
   subnetwork         = "${google_compute_subnetwork.default.name}"
 

example-gke-k8s-service-lb/main.tf

@@ -37,7 +37,7 @@ resource "google_container_cluster" "default" {
   name               = "${var.network_name}"
   zone               = "${var.zone}"
   initial_node_count = 3
-  min_master_version = "${data.google_container_engine_versions.default.latest_node_version}"
+  min_master_version = "${data.google_container_engine_versions.default.latest_master_version}"
   network            = "${google_compute_subnetwork.default.name}"
   subnetwork         = "${google_compute_subnetwork.default.name}"