This PR bumps the version of docker-maven-plugin from 0.40.2 to 0.44.0

Related Issue
None

Description of the solution adopted
Bumped the version of the docker-maven-plugin to the latest available

Screenshots
None

Any side note on the changes made
This PR has been lead to fix issue on release-1.6.x and release-1.7.x branches which are running on 0.24.0 which is no longer compatible with current Docker.
Error shown with 0.24.0:

[INFO] --- docker:0.24.0:build (build) @ kapua-assembly-java-base ---
[ERROR] DOCKER> Unable to check image [centos:7] : {"message":"client version 1.18 is too old. Minimum supported API version is 1.24, please upgrade your client to a newer version"} (Bad Request: 400) [{"message":"client version 1.18 is too old. Minimum supported API version is 1.24, please upgrade your client to a newer version"} (Bad Request: 400)]
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