Update dependency @ember/string to v4

Author: renovate[bot]

package.json

@@ -55,7 +55,7 @@
     "@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/test-setup": "^4.0.0",
     "@glimmer/component": "^1.1.2",