use node: prefix for requires

mostly because code is being autogenerated by all the AI stuff using
this prefix. it's also used in the stack trace.

src/location.js

@@ -1,6 +1,6 @@
 'use strict';
 
-const assert = require('assert');
+const assert = require('node:assert');
 
 class Location {
     constructor(subdomain, domain, type, certificate) {