refactor: to esm syntax

Author: cossssmin

lib/index.js

@@ -1,8 +1,8 @@
-const qs = require('query-string')
-const isUrl = require('is-url-superb')
-const matchHelper = require('posthtml-match-helper')
+import qs from 'query-string'
+import isUrl from 'is-url-superb'
+import matchHelper from 'posthtml-match-helper'
 
-module.exports = (config = {}) => tree => {
+const plugin = (config = {}) => tree => {
   config.strict = typeof config.strict === 'boolean' ? config.strict : true
 
   const process = node => {
@@ -49,3 +49,5 @@ module.exports = (config = {}) => tree => {
     resolve(tree)
   })
 }
+
+export default plugin