iscsi-cidr option only allows a single CIDR

When using a purestorage with many target endpoints available due to existing production outside of Openstack, it is better to specify and restrict which subnets to use for target endpoints.
Delays of 2~3 minutes have been observed in customers environment where iscsiadm would try to connect to unreachable target endpoints for each action involving an access on a volume (attaching a volume to an instance, creating a volume based on a image, ...)

For this goal, we may want to use iscsi-cidr configuration option. However as it is right now, it is only possible to specify a single subnet/CIDR.
Looking at the charm's code : https://opendev.org/openstack/charm-cinder-purestorage/src/commit/7eae2f1a7c841cc2e8898864ea67914984bf3053/src/lib/charm/openstack/cinder_purestorage.py#L44
it seems the driver uses only the 'pure_iscsi_cidr' configuration option of Purestorage driver from Openstack.

However looking at the driver itself : https://docs.openstack.org/cinder/latest/configuration/block-storage/drivers/pure-storage-driver.html
there is an option called 'pure_iscsi_cidr_list' which allows the definition of multiple CIDR/subnets instead.

The current workaround is only to configure a bigger subnet which may englobes all the wanted targets.
But if the allocated subnets are not contiguous, this may include unwanted targets addresses.