Install Terraform version 0.12
Install Terraform version 0.12

We need TF version 12 to upgrade from 0.11 to 0.13.

HashiCorp don't recommend upgrading more than one
major version at a time.

alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet