chore(deps): update terraform terraform-google-modules/cloud-nat/google to v4 (#1677)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

examples/safer_cluster_iap_bastion/network.tf

@@ -49,7 +49,7 @@ module "vpc" {
 
 module "cloud-nat" {
   source        = "terraform-google-modules/cloud-nat/google"
-  version       = "~> 3.0"
+  version       = "~> 4.0"
   project_id    = module.enabled_google_apis.project_id
   region        = var.region
   router        = "safer-router"