chore(deps): Update Terraform GoogleCloudPlatform/sql-db/google to v20 (#203)

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

Author: renovate[bot]

examples/memcache/main.tf

@@ -16,7 +16,7 @@
 
 module "private-service-access" {
   source      = "GoogleCloudPlatform/sql-db/google//modules/private_service_access"
-  version     = "~> 18.0"
+  version     = "~> 20.0"
   project_id  = var.project_id
   vpc_network = module.test-vpc-module.network_name
   depends_on = [