Updates to containerd 1.5 (oras-project#261)

containerd 1.5 is nearly out, and this is good as it supports modules
now. There's a small API break, which we should be aware of.

See https://github.com/containerd/containerd/releases/tag/v1.5.0-rc.2

Signed-off-by: Adrian Cole <[email protected]>

go.mod

@@ -10,27 +10,20 @@ replace (
 )
 
 require (
-	github.com/Azure/go-ansiterm v0.0.0-20170929234023-d6e3b3328b78 // indirect
-	github.com/Microsoft/go-winio v0.4.16 // indirect
-	github.com/Microsoft/hcsshim v0.8.14 // indirect
-	github.com/containerd/containerd v1.4.4
-	github.com/containerd/continuity v0.0.0-20201208142359-180525291bb7 // indirect
+	github.com/containerd/containerd v1.5.0-rc.2
 	github.com/docker/cli v20.10.5+incompatible
-	github.com/docker/distribution v0.0.0-20191216044856-a8371794149d
+	github.com/docker/distribution v2.7.1+incompatible
 	github.com/docker/docker v17.12.0-ce-rc1.0.20200618181300-9dc6525e6118+incompatible
 	github.com/docker/docker-credential-helpers v0.6.3 // indirect
 	github.com/docker/go-connections v0.4.0 // indirect
 	github.com/morikuni/aec v1.0.0 // indirect
 	github.com/opencontainers/go-digest v1.0.0
 	github.com/opencontainers/image-spec v1.0.1
-	github.com/opencontainers/runc v0.1.1 // indirect
 	github.com/phayes/freeport v0.0.0-20180830031419-95f893ade6f2
 	github.com/pkg/errors v0.9.1
 	github.com/sirupsen/logrus v1.8.1
 	github.com/spf13/cobra v1.1.3
 	github.com/stretchr/testify v1.7.0
-	golang.org/x/crypto v0.0.0-20201221181555-eec23a3978ad
+	golang.org/x/crypto v0.0.0-20210322153248-0c34fe9e7dc2
 	golang.org/x/sync v0.0.0-20201207232520-09787c993a3a
-	golang.org/x/sys v0.0.0-20210124154548-22da62e12c0c // indirect
-	gotest.tools/v3 v3.0.3 // indirect
 )