Null string gets encoded to null literal

[leononame]

Describe the bug

When encoding the go string "null", it gets encoded into the yaml value null, which is the null literal, rather than a yaml string.

To Reproduce

package main

import (
	"fmt"

	"github.com/goccy/go-yaml"
)

func main() {
	originalData := map[any]any{"nullString": "null", "nullValue": nil}
	// this prints:
	// map[nullString:null nullValue:<nil>]
	fmt.Printf("%v\n", originalData)

	data, _ := yaml.Marshal(originalData)
	var result map[string]any
	// yaml document:
	// nullString: null
	// nullValue: null

	// but should be:
	// nullString: "null"
	// nullValue: null
	fmt.Println(string(data))

	// after unmarshaling, we get:
	// map[nullString:<nil> nullValue:<nil>]
	yaml.Unmarshal(data, &result)
	fmt.Printf("%v\n", result)
}

Playground Link

Expected behavior

It should encode the value as "null" rather than null. See comment in code snippet above

Version Variables

• Go version: 1.21.5
• go-yaml's Version: 1.11.2