Default to Cinder v3 API

This switches the default Cinder API version to v3 to prepare for v2
going away.

Change-Id: Icca1512b715409e3001c0fd2d1ea663d5e71ec02
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>

Author: stmcginnis

openstackclient/volume/client.py

@@ -22,7 +22,7 @@
 
 LOG = logging.getLogger(__name__)
 
-DEFAULT_API_VERSION = '2'
+DEFAULT_API_VERSION = '3'
 API_VERSION_OPTION = 'os_volume_api_version'
 API_NAME = "volume"
 API_VERSIONS = {

releasenotes/notes/volume-v3-default-0ffa9bebb43b5057.yaml

@@ -0,0 +1,7 @@
+---
+upgrade:
+  - |
+    Volume commands now default to Volume API 3.  On older clouds
+    that do not support Volume 3.x ``--os-volume-api-version 2``
+    of the adition of ``volume_api_version: '2' in ``clouds.yaml``
+    will be required.