sync_render does not work with enum fields

enum fields cause errors when used in a `where` clause with `sync_render`.

`execute "CREATE TYPE todo_status AS ENUM ('pending', 'running', 'paused', 'completed', 'skipped')"`

```
sync_render(
conn,
params,
from(todo in Todo, where: todo.status in ["pending", "running", "paused"])
)
```