Add trailing newline in packages/grpc-js-xds/test/test-nack.ts

Co-authored-by: Sergii Tkachenko <hi@sergii.org>

Author: murgatroid99

packages/grpc-js-xds/test/test-nack.ts

@@ -157,4 +157,4 @@ describe('Validation errors', () => {
       }, reason => done(reason));
     }, reason => done(reason));
   });
-});
+});