Update dependency ember-cli to v6.9.1 (#318)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

package.json

@@ -60,7 +60,7 @@
     "concurrently": "9.2.1",
     "ember-auto-import": "2.12.0",
     "ember-bootstrap": "6.7.0",
-    "ember-cli": "6.8.1",
+    "ember-cli": "6.9.1",
     "ember-cli-clean-css": "3.0.0",
     "ember-cli-dependency-checker": "3.3.3",
     "ember-cli-deprecation-workflow": "3.4.0",