Upgrade influxdb python from 2.6.0 to 2.8.0
Upgrade influxdb python from 2.6.0 to 2.8.0

Change-Id: I3ba7e13b32b28944f9079c2db7bd16526481692c

openstack/monasca-persister,stackforge/monasca-persister,sapcc/monasca-persister,openstack/monasca-persister,openstack/monasca-persister,stackforge/monasca-persister,stackforge/monasca-persister