chore(deps): update dependency ember-source to v6

Author: renovate[bot]

docsSrc/package.json

@@ -55,7 +55,7 @@
     "ember-page-title": "^7.0.0",
     "ember-qunit": "^6.0.0",
     "ember-resolver": "^8.0.3",
-    "ember-source": "~4.8.0",
+    "ember-source": "~6.8.0",
     "ember-template-lint": "^4.10.0",
     "ember-welcome-page": "^6.2.0",
     "eslint": "^7.32.0",