package/docker-engine: security bump to version 19.03.11

package/docker-engine: security bump to version 19.03.11

Fixes the following security issues:

- CVE-2020-13401: Disable IPv6 Router Advertisements to prevent address
  spoofing
  An attacker in a container, with the CAP_NET_RAW capability, can craft
  IPv6 router advertisements, and consequently spoof external IPv6 hosts,
  obtain sensitive information, or cause a denial of service.

In addition, 19.03.9..11 fixes a number of issues. For details, see:

https://docs.docker.com/engine/release-notes/

Signed-off-by: Christian Stewart <christian@paral.in>
[Peter: mention security impact, extend commit message]
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>