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/notifications.js

@@ -37,7 +37,7 @@ exports = module.exports = {
     _add: add
 };
 
-const assert = require('assert'),
+const assert = require('node:assert'),
     AuditSource = require('./auditsource.js'),
     BoxError = require('./boxerror.js'),
     changelog = require('./changelog.js'),