Enable auto-terraform-governance Custom Property for Managed Repositories

[rswrz]

Description

The Terraform GitHub provider now supports custom properties.

In our organization, we have defined the custom property auto-terraform-governance, which should be set to true for all repositories managed by the terraform-governance/module-repo-setup GitHub Actions workflow.

Goal

The primary goal is to enable filtering based on custom properties instead of GitHub topics. While GitHub topics serve a different purpose, custom properties are better suited for identifying repositories that should be automatically managed.