Issue #2679883 by lokapujya: Audit use of YAML to ensure we're not using deprecated syntax

core/modules/system/tests/modules/theme_test/theme_test.services.yml

 services:
   theme_test.subscriber:
     class: Drupal\theme_test\EventSubscriber\ThemeTestSubscriber
-    arguments: [@current_route_match, @renderer]
+    arguments: ['@current_route_match', '@renderer']
     tags:
       - { name: event_subscriber }