Add missing languages:language_content context.

Author: pmelab

modules/graphql_core/tests/src/Kernel/GraphQLCoreTestBase.php

@@ -25,6 +25,7 @@ protected function defaultCacheTags() {
       'entity_bundles',
       'entity_types',
       'entity_field_info',
+      'languages:language_content',
     ], parent::defaultCacheTags());
   }