`coder templates plan` returns an empty response

reported by a user in our slack channel. i've also reproduced this behavior, using Coder version `0.22.0`

```
❯ CODER_VERBOSE=true coder templates plan aws-ec2

❯ coder templates list
NAME         LAST UPDATED    USED BY              
aws-ec2      April 11, 2023  1 active developer
```

