Empty null value gets converted to "null" in token

[Mike Farah]

Describe the bug
A clear and concise description of what the bug is.

To Reproduce

cat:

See https://play.golang.com/p/FCsVZ8eQ1J6

Expected behavior

The ast token Origin (or value) would have the string value of ""

Version Variables

• go version go1.21.0 linux/amd64
• go-yaml's Version: v1.11.2

Additional context
I'm looking to replace yq's yaml engine with goccy!

[Updated] Fixed goplay link!