convert to ESM

package.json

@@ -1,4 +1,5 @@
 {
+  "type": "module",
   "dependencies": {
     "mime": "*"
   }

sfs.js

@@ -1,12 +1,10 @@
 #!/usr/bin/env node
 
-'use strict';
-
-const fs = require('fs');
-const http = require('http');
-const mime = require('mime');
-const readline = require('readline');
-const util = require('util');
+import fs from 'fs';
+import http from 'http';
+import mime from 'mime';
+import readline from 'readline';
+import util from 'util';
 
 const readdir = util.promisify(fs.readdir);
 const stat = util.promisify(fs.stat);