chore: set the aion-team as code owners on google-auth-library-nodejs (#8084)

* chore: set the aion-team as code owners on google-auth-library-nodejs so they can be set as reviewers

* add new line in response to gemini code review

Author: pearigee

.github/CODEOWNERS

@@ -15,3 +15,4 @@
 /handwritten/bigquery-storage @googleapis/bigquery-team
 /handwritten/pubsub @googleapis/pubsub-team
 /handwritten/bigtable @googleapis/bigtable-team
+/core/packages/google-auth-library-nodejs @googleapis/aion-team