Upgrade a11y testing since the prior version had too narrow of a peer range on test-helpers

Author: NullVoxPopuli

docs-app/package.json

@@ -88,7 +88,7 @@
     "autoprefixer": "^10.4.19",
     "broccoli-asset-rev": "^3.0.0",
     "concurrently": "^8.2.2",
-    "ember-a11y-testing": "^6.1.1",
+    "ember-a11y-testing": "^7.0.0",
     "ember-auto-import": "^2.5.0",
     "ember-cached-decorator-polyfill": "^1.0.2",
     "ember-cli": "~5.8.1",