We don't need to downgrade those

Author: NullVoxPopuli

test-app/config/ember-try.js

@@ -11,9 +11,7 @@ module.exports = async function () {
         name: 'ember-lts-3.28',
         npm: {
           devDependencies: {
-            '@ember/test-helpers': '^2.9.3',
             'ember-cli': '~4.12.0',
-            'ember-qunit': '^6.0.0',
             'ember-source': '~3.28.0',
             'babel-plugin-ember-polyfill-get-and-set-owner-from-ember-owner':
               '^1.0.0',