Add RBAC test for updating volume group

This commit adds a test for updating a volume group, providing
coverage for group:update policy action.

Change-Id: Ifc6ccb8d79fa01c3dfe951282e004f79db2d01cd
diff --git a/releasenotes/notes/update-group-volume-test-06c7475ccbe36aa8.yaml b/releasenotes/notes/update-group-volume-test-06c7475ccbe36aa8.yaml
new file mode 100644
index 0000000..77cf196
--- /dev/null
+++ b/releasenotes/notes/update-group-volume-test-06c7475ccbe36aa8.yaml
@@ -0,0 +1,5 @@
+---
+features:
+  - |
+    Add test for updating a volume group, providing coverage for group:update
+    policy action.