Upgrade Docker to 19.03.12

[martinxsliu]

This PR updates the version of Docker to 19.03.12. In particular the latest versions of Docker use api version 1.40, while the current version (18.09.8) uses api version 1.39 and updating should address versioning issues like https://github.com/kubernetes-sigs/kubespray/issues/6160.

I have built and used the image, and can confirm that the new version works as expected.

[zoonage]

@meAmidos is there a plan to merge this?

[pratikbin]

Waiting for this one to merge, thanks for testing @martinxsliu