Update .gitlab-ci.yml file to include k8s v1.19

Update .gitlab-ci.yml file to include k8s v1.19
tags

This change updates the .gitlab-ci.yml file to
include the k8s release v1.19 tags supported
by the new BMRA v21.03 release.

Change-Id: I70df4f1682e974b7d46b0c9d40d71fab4851b702
Signed-off-by: Rihab Banday <rihab.banday@ericsson.com>
Reviewed-on: https://gerrit.opnfv.org/gerrit/c/kuberef/+/72475
Tested-by: jenkins-ci <jenkins-opnfv-ci@opnfv.org>
Reviewed-by: Michael Pedersen <michaelx.pedersen@intel.com>
Reviewed-by: Cedric Ollivier <cedric.ollivier@orange.com>