Fixed IDE derp with requring assert

- I don't know how this happened or why it worked locally :woman-shrugging::skin-tone-2:
- seems like my IDE did a fart and I didn't notice.

test/utils/e2e-framework-mock-utils.js

@@ -1,6 +1,6 @@
 const errors = require('@tryghost/errors');
 const sinon = require('sinon');
-const assert = require('node:assert');
+const assert = require('assert');
 
 let mocks = {};
 let emailCount = 0;