chore(deps): update dependency ember-source to ~6.8.0

Author: renovate[bot]

ember-file-upload/package.json

@@ -76,7 +76,7 @@
     "concurrently": "^9.0.0",
     "ember-cli-htmlbars": "^6.1.1",
     "ember-modifier": "^3.2.7",
-    "ember-source": "~6.4.0",
+    "ember-source": "~6.8.0",
     "ember-template-lint": "^5.0.0",
     "eslint": "^8.42.0",
     "eslint-config-prettier": "^9.0.0",