fix(server): missing dependency in sync app (#4465)

apps/server/tests/sync.spec.ts

@@ -0,0 +1,16 @@
+import { Test } from '@nestjs/testing';
+import test from 'ava';
+
+test('should be able to bootstrap sync server', async t => {
+  // set env before import
+  process.env.SERVER_FLAVOR = 'sync';
+  const { AppModule } = await import('../src/app');
+  await t.notThrowsAsync(async () => {
+    const module = await Test.createTestingModule({
+      imports: [AppModule],
+    }).compile();
+    const app = module.createNestApplication();
+    await app.close();
+  });
+  process.env.SERVER_FLAVOR = '';
+});