chore: add TODO for future encoding of all non-alphanumerical characters

Author: panva

lib/helpers/client.js

@@ -9,6 +9,7 @@ const request = require('./request');
 const { keystores } = require('./weak_cache');
 const merge = require('./merge');
 
+// TODO: in v6.x additionally encode the `- _ . ! ~ * ' ( )` characters
 const formUrlEncode = (value) => encodeURIComponent(value).replace(/%20/g, '+');
 
 async function clientAssertion(endpoint, payload) {