chore(CI): bump machine type (terraform-google-modules#1882)

Author: apeabody

examples/simple_zonal_with_asm/main.tf

@@ -50,7 +50,7 @@ module "gke" {
  autoscaling = false
  auto_upgrade = true
  node_count = 3
- machine_type = "e2-standard-4"
+ machine_type = "e2-standard-8"
  },
  ]
 }