chg: dev: Modifying regex for show dhcp-server
chg: dev: Modifying regex for show dhcp-server

Fixing regex for IPv6 static leases

Change-Id: I1a836ad000b7dce9db4570bba91203731aa77283
Signed-off-by: Jose Calvo <1e262b0ba158f66a63f61a7916cbdf3098f63044@hpe.com>

open-switch/ops-topology-lib-vtysh