3.28 is old enough where we need to downgrade more dependencies

Author: NullVoxPopuli

test-app/config/ember-try.js

@@ -11,6 +11,7 @@ module.exports = async function () {
         npm: {
           devDependencies: {
             'ember-source': '~3.28.0',
+            'ember-cli': '~3.28.0',
           },
         },
       },