Update terraform version constraint

There is no "google_project" resource managed by terraform, so we are not worried about the new terraform binary destroying/re-creating GAE resources.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=217206226

java/google/registry/proxy/terraform/modules/common.tf

@@ -1,4 +1,4 @@
 provider "google" {
-  version = "<= 1.12.0"
+  version = ">= 1.13.0"
   project = "${var.proxy_project_name}"
 }