maint-lib: make git fetch silent
maint-lib: make git fetch silent

This fixes the script integration by silencing any output.

Signed-off-by: Sébastien Han <62d754cc350e84d3b1c32ae79f976f5348e74a40@redhat.com>

ceph/ceph-docker,JrCs/ceph-docker,JrCs/ceph-docker,JrCs/ceph-docker,ceph/ceph-docker