fix: use fs/promises instead of util.promisify (#180)

lib/is.js

@@ -1,6 +1,4 @@
 // not an airtight indicator, but a good gut-check to even bother trying
-const { promisify } = require('util')
-const fs = require('fs')
-const stat = promisify(fs.stat)
+const { stat } = require('fs/promises')
 module.exports = ({ cwd = process.cwd() } = {}) =>
  stat(cwd + '/.git').then(() => true, () => false)