Update dependency @ember/test-helpers to v5.4.0

Author: renovate[bot]

package.json

@@ -44,7 +44,7 @@
     "@babel/eslint-parser": "7.28.4",
     "@babel/plugin-proposal-decorators": "7.28.0",
     "@ember/optional-features": "2.2.0",
-    "@ember/test-helpers": "5.3.0",
+    "@ember/test-helpers": "5.4.0",
     "@embroider/macros": "1.19.2",
     "@embroider/test-setup": "4.0.0",
     "@eslint/js": "9.38.0",