Update docker

Changes:

- https://github.com/docker-library/docker/commit/9c726fa: Merge pull request https://github.com/docker-library/docker/pull/211 from infosiftr/alpine3.11
- https://github.com/docker-library/docker/commit/a4b5e1b: Update to Alpine 3.11

library/docker

@@ -6,7 +6,7 @@ GitRepo: https://github.com/docker-library/docker.git
 
 Tags: 19.03.5, 19.03, 19, stable, test, latest
 Architectures: amd64, arm32v6, arm32v7, arm64v8
-GitCommit: 7a67842e7ff12c1426ae6a67ac1b7a701b51f3df
+GitCommit: a4b5e1b043432fc16fbe983a4bb2e1a004db2aca
 Directory: 19.03
 
 Tags: 19.03.5-dind, 19.03-dind, 19-dind, stable-dind, test-dind, dind