fix(infra): Redis 镜像更换为 redis:7，移除过时的 version 字段

Made-with: Cursor

deploy/docker-compose.dev.yml

@@ -1,5 +1,3 @@
-version: '3.8'
-
 services:
   postgres:
     image: postgres:17
@@ -20,7 +18,7 @@ services:
       retries: 5
 
   redis:
-    image: redis:7-alpine
+    image: redis:7
     container_name: echochat-redis
     ports:
       - "6379:6379"