changed docker file nest to avoid rebuild everything each time, and small changes in chat gateway

tests_hugo/nest_course/src/main.ts

@@ -0,0 +1,8 @@
+import { NestFactory } from '@nestjs/core';
+import { AppModule } from './app.module';
+
+async function bootstrap() {
+  const app = await NestFactory.create(AppModule);
+  await app.listen(3000);
+}
+bootstrap();