Update dependency @ember/test-helpers to v5

Author: renovate[bot]

package.json

@@ -60,7 +60,7 @@
     "@ember/optional-features": "2.2.0",
     "@ember/render-modifiers": "2.1.0",
     "@ember/string": "3.1.1",
-    "@ember/test-helpers": "4.0.5",
+    "@ember/test-helpers": "5.1.0",
     "@ember/test-waiters": "3.1.0",
     "@embroider/compat": "3.8.0",
     "@embroider/core": "3.5.0",