Update test matrix for Sanic #476

Job	Run time
Tasks (pinned) (3.6, ubuntu-20.04)	3m 29s
Tasks (pinned) (3.7, ubuntu-20.04)	4m 2s
Tasks (pinned) (3.8, ubuntu-20.04)	4m 32s
Tasks (pinned) (3.9, ubuntu-20.04)	2m 11s
Tasks (pinned) (3.10, ubuntu-20.04)	4m 10s
Tasks (pinned) (3.11, ubuntu-20.04)	5m 5s
Tasks (pinned) (3.12, ubuntu-20.04)	4m 7s
Tasks (latest) (3.6, ubuntu-20.04)	1m 18s
Tasks (latest) (3.7, ubuntu-20.04)	2m 25s
Tasks (latest) (3.8, ubuntu-20.04)	3m 49s
Tasks (latest) (3.10, ubuntu-20.04)	2m 52s
Tasks (latest) (3.11, ubuntu-20.04)	3m 31s
Tasks (latest) (3.12, ubuntu-20.04)	4m 55s
Tasks (latest) (3.13, ubuntu-20.04)	4m 46s
All pinned Tasks tests passed	1s
	51m 13s

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