add aarch64 to systems #589

Job	Run time
build (nix-snapshotter)	1m 45s
lint (golangci-lint)	2s
build (image-hello)	1m 34s
build (image-redis)	1m 36s
build (image-redisWithShell)	1m 38s
integration-test (snapshotter)	4m 53s
integration-test (push-n-pull)	4m 6s
integration-test (kubernetes)	5m 3s
integration-test (k3s)	13m 10s
integration-test (k3s-external)	14m 51s
integration-test (k3s-rootless)	13m 9s
integration-test (gvisor)	4m 2s
coverage-report	3m 9s
	1h 8m 58s

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