Pin jnr-unixsocket for Docker plugin to 0.13

Pin jnr-unixsocket for Docker plugin to 0.13

The current verison of jnr-unixsocket is 0.12 from the Docker
plugin however in order to be able the images for ARM64, it needs
the newer version which has support for it.

There is work upstream to switch the version to 0.18[0] however
it seems that this is still pending, so we can pin it for now until
that merges.

[0]: https://github.com/spotify/docker-maven-plugin/pull/379

Change-Id: Ic2559c8371b249f5a3f7de01d30d773d9b5d876f
Issue-ID: CIMAN-154
Signed-off-by: Mohammed Naser <mnaser@vexxhost.com>