fix: "isPlainObject is not a function" in browser builds (#51)

Author: hughrawlinson

lib/request.js

@@ -1,6 +1,6 @@
 module.exports = request
 
-const isPlainObject = require('is-plain-object')
+const isPlainObject = require('is-plain-object/index.cjs.js')
 const nodeFetch = require('node-fetch').default
 
 const getBuffer = require('./get-buffer-response')