Recreate Timer object before starting

Since this can be reused, you can't restart Timers, so create a new one.

sound.py

@@ -51,6 +51,7 @@ def main():
  pg.mixer.Channel(1).play(stageOne)
  elif messagedata == b"stage_2_separation":
  pg.mixer.Channel(2).play(stageTwo)
+ t = Timer(30.0, endMission)
  t.start()
  else:
  print("Unhandled message")