Multiline string marshalling creates unneccesary escapes

[0xf0xx0]

Describe the bug
When marshalling a multiline string, go-toml/v2 escapes quotes that don't need to be.

To Reproduce

type Foo struct {
	Foo string `toml:"foo,multiline"`
}
s := Foo{
	Foo: "bar\n\"baz\"\n\"bam\n",
}
enc, _ := toml.Marshal(s)
println(string(enc))

The output is:

foo = """
bar
\"baz\"
\"bam
"""

Expected behavior
I expected the output to be

foo = """
bar
"baz"
"bam
"""

Versions

• go-toml: v2.2.4
• go: 1.24.3
• operating system: Linux