Fix docker default database env variables (#874)

Author: wu-clan

deploy/backend/docker-compose/.env.server

@@ -1,10 +1,10 @@
 # Env
 ENVIRONMENT='prod'
 # Database
-DATABASE_TYPE='mysql'
-DATABASE_HOST='fba_mysql'
-DATABASE_PORT=3306
-DATABASE_USER='root'
+DATABASE_TYPE='postgresql'
+DATABASE_HOST='fba_postgres'
+DATABASE_PORT=5432
+DATABASE_USER='postgres'
 DATABASE_PASSWORD='123456'
 # Redis
 REDIS_HOST='fba_redis'