feat: enable async

Author: woowahan-neo

backend/src/main/java/wooteco/prolog/AsyncConfig.java

@@ -0,0 +1,9 @@
+package wooteco.prolog;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.scheduling.annotation.EnableAsync;
+
+@Configuration
+@EnableAsync
+public class AsyncConfig {
+}