feat: upgrade OpenTofu versions

This change adds a new manager and post upgrade task for the OpenTofu CI/CD component that upgrades the latest supported OpenTofu version and adds it to the list of supported versions.

Removal of older versions is taking care of by the components maintainers not (yet) part of the renovate setup.

The called .gitlab/scripts/renovate-post-upgrade.sh script simply takes the updates latest_version from the opentofu_versions.yaml file that has been updated by renovate and prepends that version to the list of supported versions.

The script has a requirements of yq.