Support OS version in platform string #5196

Job	Run time
prepare	1s
test / prepare	2m 21s
test / run (containerd, ./frontend/dockerfile, integration)	4m 8s
test / run (containerd, ./frontend/dockerfile, dockerfile)	4m 8s
test / run (containerd-rootless, ./frontend/dockerfile, integration)	4m 6s
test / run (containerd-rootless, ./frontend/dockerfile, dockerfile)	4m 8s
test / run (containerd-1.6, ./frontend/dockerfile, integration)	4m 9s
test / run (containerd-1.6, ./frontend/dockerfile, dockerfile)	4m 8s
test / run (containerd-1.7, ./frontend/dockerfile, integration)	4m 11s
test / run (containerd-1.7, ./frontend/dockerfile, dockerfile)	4m 13s
test / run (containerd-snapshotter-stargz, ./frontend/dockerfile, integration)	4m 5s
test / run (containerd-snapshotter-stargz, ./frontend/dockerfile, dockerfile)	4m 5s
test / run (oci, ./frontend/dockerfile, integration)	4m 6s
test / run (oci, ./frontend/dockerfile, dockerfile)	4m 6s
test / run (oci-rootless, ./frontend/dockerfile, integration)	4m 6s
test / run (oci-rootless, ./frontend/dockerfile, dockerfile)	4m 6s
test / run (oci-rootless-slirp4netns-detachnetns, ./frontend/dockerfile, integration)	4m 7s
test / run (oci-rootless-slirp4netns-detachnetns, ./frontend/dockerfile, dockerfile)	4m 5s
test / run (oci-snapshotter-stargz, ./frontend/dockerfile, integration)	4m 6s
test / run (oci-snapshotter-stargz, ./frontend/dockerfile, dockerfile)	4m 10s
image	1s
scout	1s
release	1s
	1h 16m 38s

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