tests/acceptance/404: Migrate from mirage to @crates-io/msw

Author: Turbo87

tests/acceptance/404-test.js

@@ -6,7 +6,7 @@ import percySnapshot from '@percy/ember';
 import { setupApplicationTest } from 'crates-io/tests/helpers';
 
 module('Acceptance | 404', function (hooks) {
-  setupApplicationTest(hooks);
+  setupApplicationTest(hooks, { msw: true });
 
   test('/unknown-route shows a 404 page', async function (assert) {
     await visit('/unknown-route');