fix: boolean-string converted to string

[0xthierry]

Issue

The BooleanString converted value is a string instead of a boolean. This occurs because Typebox converts the value to the first matching schema, as shown here:

function FromUnion(schema: TUnion, references: TSchema[], value: any): unknown {
  for (const subschema of schema.anyOf) {
    const converted = Visit(subschema, references, value)
    if (!Check(subschema, references, converted)) continue
    return converted
  }
  return value
}

[sofyanox12]

Just realized this. Very straightforward and should've been merged.