minor code cleanup

src/main.ts

@@ -2,9 +2,9 @@ import { NestFactory } from '@nestjs/core';
 import { AppModule } from './app.module';
 import { NestExpressApplication } from '@nestjs/platform-express';
 
-async function bootstrap() {
+async function bootstrap(): Promise<void> {
   const app = await NestFactory.create<NestExpressApplication>(AppModule);
   app.setGlobalPrefix('common-cents');
   await app.listen(process.env.PORT ?? 3000);
 }
-bootstrap();
+void bootstrap();