extension key `template_driver` does not start with "x-"

Cool project, thanks for the work! I'm exploring converting our [large collection](https://git.coopcloud.tech/coop-cloud) of compose configs into quadlet files to support podman users. I ran into this error straight away.

```
➜ ~ podlet compose compose.yml
Error:
0: error converting compose file
1: error reading compose file
2: File `/home/d1/.abra/recipes/custom-html/compose.yml` is not a valid compose file
3: extension key `template_driver` does not start with "x-"
```

This compose file: https://git.coopcloud.tech/coop-cloud/custom-html/src/branch/main/compose.yml

If I add the `x-...` it then complains about `name` and eventually that `configs` are not supported?