ci: use edge releases of buildx #4974

Job	Run time
prepare	1s
test / prepare	1m 58s
test / run (containerd, ./frontend/dockerfile, integration)	5m 12s
test / run (containerd, ./frontend/dockerfile, dockerfile)	6m 50s
test / run (containerd-rootless, ./frontend/dockerfile, integration)	5m 11s
test / run (containerd-rootless, ./frontend/dockerfile, dockerfile)	7m 8s
test / run (containerd-1.6, ./frontend/dockerfile, integration)	5m 7s
test / run (containerd-1.6, ./frontend/dockerfile, dockerfile)	7m 0s
test / run (containerd-1.7, ./frontend/dockerfile, integration)	4m 57s
test / run (containerd-1.7, ./frontend/dockerfile, dockerfile)	7m 30s
test / run (containerd-snapshotter-stargz, ./frontend/dockerfile, integration)	5m 0s
test / run (containerd-snapshotter-stargz, ./frontend/dockerfile, dockerfile)	8m 49s
test / run (oci, ./frontend/dockerfile, integration)	4m 23s
test / run (oci, ./frontend/dockerfile, dockerfile)	6m 5s
test / run (oci-rootless, ./frontend/dockerfile, integration)	5m 1s
test / run (oci-rootless, ./frontend/dockerfile, dockerfile)	6m 14s
test / run (oci-rootless-slirp4netns-detachnetns, ./frontend/dockerfile, integration)	4m 24s
test / run (oci-rootless-slirp4netns-detachnetns, ./frontend/dockerfile, dockerfile)	5m 57s
test / run (oci-snapshotter-stargz, ./frontend/dockerfile, integration)	4m 28s
test / run (oci-snapshotter-stargz, ./frontend/dockerfile, dockerfile)	6m 8s
image (mainline)	5m 12s
image (labs)	5m 25s
scout	0s
release	0s
	1h 58m 0s

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