add redis as required

README.md

 
 # Install
 
-OS require: build-essential libsdl1.2debian libsdl-image1.2 libsdl-image1.2-dev libsdl-ttf2.0-0 libsdl-ttf2.0-dev libsdl-mixer1.2 libsdl-mixer1.2-dev
+OS require: build-essential libsdl1.2debian libsdl-image1.2 libsdl-image1.2-dev libsdl-ttf2.0-0 libsdl-ttf2.0-dev libsdl-mixer1.2 libsdl-mixer1.2-dev redis-server
 
 Python version: 3.5+