Release 3.18.0 Changelog (#1965)
Release 3.18.0 Changelog (#1965)

* update changelog (#1955)

* v3.18.0

* Add next release placeholder

Co-authored-by: tf-release-bot <75ada95d871dcca86237fcab94575a31d1b359cf@hashicorp.com>
hashicorp/terraform-provider-google-beta,hashicorp/terraform-provider-google-beta,hashicorp/terraform-provider-google-beta,hashicorp/terraform-provider-google-beta