test: add instance verification test case

tests/unit/server.test.ts

@@ -62,6 +62,7 @@ describe('WebhookServer', () => {
   });
 
   test('should verify instance name', async () => {
+    process.env.TEST_VERIFY_INSTANCE = 'true';
     const payload = {
       event: 'messages.upsert',
       instance: 'wrong-instance',