HAML "attrr-double quotes" grunt build config

Gruntfile.js

module.exports = function(grunt) {
    grunt.initConfig({
        haml: {
            dist: {
                options: {
                    "double-quote-attributes": true,
                    style: 'expanded'
                },
                files: {
                    'index.html': 'index.haml'
                }
            }
        }
    });
    grunt.loadNpmTasks('grunt-contrib-haml');
    grunt.registerTask('default', ['haml']);
};