packer-sdc struct-markdown is stuck doing nothing

#### Overview of the Issue

Using below code with `go generate -v -x`
```go
//go:generate packer-sdc struct-markdown
//go:generate packer-sdc mapstructure-to-hcl2 -type ProvisionerConfig
```

will get stuck forever doing nothing
```sh=bash
❯ go generate -v -x
data.go
packer-sdc mapstructure-to-hcl2 -type DataSourceOutput,DataSourceConfig
data.hcl2spec.go
main.go
post-processor.go
packer-sdc mapstructure-to-hcl2 -type PostProcessorConfig
post-processor.hcl2spec.go
provisioner.go
packer-sdc struct-markdown
```

#### Reproduction Steps

```sh=bash
git clone https://git.panekj.dev/pj/packer-plugin-http.git
cd packer-plugin-http
go generate -v -x
```

### Packer Plugin SDK version

`packersdk.Version`

```sh=bash
❯ packer-sdc --version
0.4.0
```

```gomod
require (
github.com/hashicorp/hcl/v2 v2.14.1
github.com/hashicorp/packer-plugin-sdk v0.4.0
github.com/zclconf/go-cty v1.10.0
golang.org/x/net v0.8.0
)
```

Same thing happening on `0.3.4`

### Operating system and Environment details

OS: `macOS 13.1`
Architecture: `arm64`
```sh=bash
❯ go version
go version go1.20.2 darwin/arm64
```

can reproduce it on Ubuntu 22.04 x64