YAML parsing is not as expected

In theory, data in json format should not be parsed into data in a structure.

<img width="656" alt="image" src="https://github.com/go-yaml/yaml/assets/49381700/cf5d76ca-a0ad-46e2-bd49-adc901c24b83">

This problem was discovered when I was writing gin test cases. (See [Issue](https://github.com/gin-gonic/gin/issues/3862))
