improve the influxdb-python version
improve the influxdb-python version

We should set the influxdb-python version at least 2.4.0 tag which
shows influxdb>=2.4 in test-requirements.txt. Because we have used
the key 'measurement' that appears after tag 2.4.0 in which points
by influxdb storage. We can see the README Examples at
https://github.com/influxdb/influxdb-python/tree/v2.2.0 and
https://github.com/influxdb/influxdb-python/tree/v2.4.0 respectively.

Change-Id: I7aa7d4a708c035890a73f5899d1d6683a99c9210

sileht/gnocchi,leandroreox/gnocchi,gnocchixyz/gnocchi,gnocchixyz/gnocchi,sileht/gnocchi,leandroreox/gnocchi