Update docker

Changes:

- docker-library/docker@a2f8c1c: Merge pull request docker-library/docker#319 from infosiftr/zombie-workaround
- docker-library/docker@8baa881: Add (hopefully temporary) workaround for containerd-shim zombies

library/docker

@@ -11,7 +11,7 @@ Directory: 20.10
 
 Tags: 20.10.7-dind, 20.10-dind, 20-dind, dind
 Architectures: amd64, arm32v6, arm32v7, arm64v8
-GitCommit: 30d7b9bf7663c96fcd888bd75e9aaa547a808a23
+GitCommit: 8baa881aab85f8398d2edbbcc0da4bd1f556dd98
 Directory: 20.10/dind
 
 Tags: 20.10.7-dind-rootless, 20.10-dind-rootless, 20-dind-rootless, dind-rootless
@@ -38,7 +38,7 @@ Directory: 19.03
 
 Tags: 19.03.15-dind, 19.03-dind, 19-dind
 Architectures: amd64, arm32v6, arm32v7, arm64v8
-GitCommit: f0abe5a51a683c02501fd7ff8384fb17dbbeb946
+GitCommit: 8baa881aab85f8398d2edbbcc0da4bd1f556dd98
 Directory: 19.03/dind
 
 Tags: 19.03.15-dind-rootless, 19.03-dind-rootless, 19-dind-rootless