fix the rendering bug of MPE environment #932

Job	Run time
tutorial-test (3.8, Tianshou)	3m 15s
tutorial-test (3.8, CustomEnvironment)	33s
tutorial-test (3.8, CleanRL)	8m 39s
tutorial-test (3.8, SB3/kaz)	7m 45s
tutorial-test (3.8, SB3/waterworld)	10m 32s
tutorial-test (3.8, SB3/connect_four)	2m 59s
tutorial-test (3.8, SB3/test)	2m 11s
tutorial-test (3.9, Tianshou)	3m 14s
tutorial-test (3.9, CustomEnvironment)	35s
tutorial-test (3.9, CleanRL)	6m 56s
tutorial-test (3.9, SB3/kaz)	7m 43s
tutorial-test (3.9, SB3/waterworld)	7m 47s
tutorial-test (3.9, SB3/connect_four)	4m 51s
tutorial-test (3.9, SB3/test)	2m 3s
tutorial-test (3.10, Tianshou)	4m 15s
tutorial-test (3.10, CustomEnvironment)	34s
tutorial-test (3.10, CleanRL)	6m 57s
tutorial-test (3.10, SB3/kaz)	4m 43s
tutorial-test (3.10, SB3/waterworld)	7m 58s
tutorial-test (3.10, SB3/connect_four)	4m 11s
tutorial-test (3.10, SB3/test)	2m 4s
tutorial-test (3.11, Tianshou)	3m 18s
tutorial-test (3.11, CustomEnvironment)	26s
tutorial-test (3.11, CleanRL)	10m 29s
tutorial-test (3.11, SB3/kaz)	7m 36s
tutorial-test (3.11, SB3/waterworld)	9m 27s
tutorial-test (3.11, SB3/connect_four)	3m 59s
tutorial-test (3.11, SB3/test)	3m 24s
	2h 18m 24s

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