If a template changes, the user may update an associated workspace, either in the CLI (coder update "workspace-1"), or in the UI:

Additionally, in the future, we might make it possible for users to toggle between template versions in the UI.

We should audit these template version changes. One easy way might be to include the template_version_id in the workspace build diff, but we should check that 1) this works when we're updating via the CLI and 2) that this satisfies the product requirement, as we won't have a separate line item for workspace template changes.