Update dependency ember-source to v6

Author: renovate[bot]

package.json

@@ -51,7 +51,7 @@
     "ember-page-title": "7.0.0",
     "ember-qunit": "9.0.2",
     "ember-resolver": "10.1.1",
-    "ember-source": "5.12.0",
+    "ember-source": "6.4.0",
     "ember-template-lint": "7.6.0",
     "ember-try": "2.0.0",
     "eslint": "9.26.0",