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

.env.sample

@@ -18,7 +18,7 @@ DATABASE_CONNECTION_POOL_MAX=
 # PGSSLMODE=disable
 
 # For redis you can either specify an ioredis compatible url like this
-REDIS_URL=redis://localhost:6479
+REDIS_URL=redis://localhost:6379
 # or alternatively, if you would like to provide addtional connection options,
 # use a base64 encoded JSON connection option object. Refer to the ioredis documentation
 # for a list of available options.