Fix game start room

Game start room was accidentally hardcoded to be "prelude" instead of
using the start_room variable. This is fixed.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

agame/__main__.py

@@ -28,7 +28,7 @@ start_room = game_module.start_room  # type: ignore
 game = Game(
     display=ANSIDisplay(),
     database=database,
-    room=database.rooms["prelude"],
+    room=database.rooms[start_room],
 )
 
 try: