Update redis port in sample env file (#3596)

* fix redis port

The wrong Redis port is specified in the sample file, we fixed that

* adjust redis port in docker-compose

docker-compose.yml

@@ -3,7 +3,7 @@ services:
   redis:
     image: redis
     ports:
-      - "127.0.0.1:6479:6379"
+      - "127.0.0.1:6379:6379"
     user: "redis:redis"
   postgres:
     image: postgres