fix: remove invalid expose from frontend service

The frontend service incorrectly exposed MySQL port 3306, which is not required
since it doesn't run any database. This commit removes the unnecessary expose 
directive and ensures that only the db service exposes the appropriate ports.

Signed-off-by: Bokyeom <79684339+k-kbk@users.noreply.github.com>

react-java-mysql/compose.yaml

@@ -32,6 +32,9 @@ services:
       - db-data:/var/lib/mysql
     networks:
       - spring-mysql
+    expose:
+      - 3306
+      - 33060
   frontend:
     build:
       context: frontend
@@ -45,9 +48,6 @@ services:
       - react-spring
     depends_on:
       - backend
-    expose:
-      - 3306
-      - 33060
 volumes:
   db-data: {}
 secrets: