Yaml library drops comments when round tripping

**Describe the bug**

If I parse a yaml file, edit it then save it back, it drops all comments.

**Steps to Reproduce**

```ts
import {
parse,
stringify,
} from "https://deno.land/std@0.182.0/yaml/mod.ts";

const result = stringify(parse(`
# comment
name: example
`));

console.log(stringify(result)) // name: example
```

**Expected behavior**

I expect all code comments to be preserved.

**Environment**

```
deno 1.31.3 (release, x86_64-apple-darwin)
v8 11.0.226.19
typescript 4.9.4
```
- std version: `0.182.0`