Upgrade ember-cli in the docs-app

Author: NullVoxPopuli

docs/package.json

@@ -37,7 +37,7 @@
     "@typescript-eslint/parser": "^6.15.0",
     "broccoli-asset-rev": "^3.0.0",
     "ember-auto-import": "^2.0.0",
-    "ember-cli": "~3.28.3",
+    "ember-cli": "~4.12.1",
     "ember-cli-babel": "^8.2.0",
     "ember-cli-code-coverage": "^2.0.3",
     "ember-cli-dependency-checker": "^3.2.0",