chore(deps): update dependency @ember/string to v4

Author: renovate[bot]

packages/test-app/package.json

@@ -33,7 +33,7 @@
     "@babel/eslint-parser": "7.25.1",
     "@babel/plugin-proposal-decorators": "7.24.7",
     "@ember/optional-features": "2.1.0",
-    "@ember/string": "3.1.1",
+    "@ember/string": "4.0.0",
     "@ember/test-helpers": "3.3.1",
     "@embroider/compat": "3.6.1",
     "@embroider/core": "3.4.15",