v1.18.0

• New resource: postgresql_server and postgresql_user_mapping - @fabiopaiva
  #220

• New resource: postgresql_subscription - @nicarl
  #244

• Allow to configure AWS Region with AWS IAM Auth - @bpaquet
  #260

• Create temporary file for GOOGLE_APPLICATION_CREDENTIALS in Terraform cloud - @minkainc-opensource
  #249

FIX:

• postgresql_grant: Concurrency issue on database privileges - @timothegenzmer
  #224

• postgresql_grant: Remove TEMP privileges for database - @cyrilgdn
  #243

DEV IMPROVEMENTS:

• Update Postgres versions in tests - @cyrilgdn