openstackclient doesn't support volume API microversions

Issue

• Various openstack ... commands print the following error when using --os-volume-api-version 3.xx or have OS_VOLUME_API_VERSION=3.xx environment variable:

  volume version 3.48 is not in supported versions: 1, 2, 3
  Invalid volume client version '3.48'. must be one of: 1, 2, 3
  

• python-openstackclient doesn't support microversions for Volume API