0.6.0 Update `terraform-external-module-artifact` version

what

• Update terraform-external-module-artifact version

why

• Add enabled variable to the module
• When the terraform-external-module-artifact module is used in this module with enabled variable set to false, terraform-external-module-artifact needs to be disabled as well (otherwise it throws errors that it can't download the artifact)

references

• https://github.com/cloudposse/terraform-external-module-artifact/releases/tag/0.3.0