[cern] Update traefik options
Upstream: https://review.opendev.org/c/openstack/magnum/+/783390
- Traefik version updated from v1.7.19 to v1.7.28
- Force secure connections to use TLSv1.2 or greater
Change-Id: I65561358113952e3f60dc488b35ee8fa8f8da740 Signed-off-by: Diogo Guerra diogo.filipe.tomas.guerra@cern.ch