package/docker-engine: bump version to 20.10.6

package/docker-engine: bump version to 20.10.6

Fixes various networking issues:

- Fix a regression in docker 20.10, causing IPv6 addresses no longer to be
  bound by default when mapping ports moby/moby#42205

- Fix implicit IPv6 port-mappings not included in API response.  Before
  docker 20.10, published ports were accessible through both IPv4 and IPv6
  by default, but the API only included information about the IPv4 (0.0.0.0)
  mapping moby/moby#42205

- Fix a regression in docker 20.10, causing the docker-proxy to not be
  terminated in all cases moby/moby#42205

- Fix iptables forwarding rules not being cleaned up upon container removal
  moby/moby#42205

For more details, see the release notes:
https://docs.docker.com/engine/release-notes/#20106

Signed-off-by: Mario Fink <knif.oiram@gmail.com>
Tested-by: Christian Stewart <christian@paral.in>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>