Cinder stable/ussuri release for os-brick

The reason for this quick release after the previous ussuri
release (3.0.5 on 11 March, 2021) is the inclusion of a critical
os-brick patch[1] that fixes a potential data loss situation.

[1] https://review.opendev.org/c/openstack/os-brick/+/784095

Change-Id: I4c30de49d40c79ae7ed54b158ed4250e6488073e

deliverables/ussuri/os-brick.yaml

@@ -35,6 +35,10 @@ releases:
     projects:
       - repo: openstack/os-brick
         hash: 2611c32d7afc895b3bc80d399e2a0843d64f6447
+  - version: 3.0.6
+    projects:
+      - repo: openstack/os-brick
+        hash: 4894b242cf97f6630ee21392443ddb3ce1be09ef
 branches:
   - location: 3.0.1
     name: stable/ussuri