Fix gate for multiple issues

1. To have mock installed for unit tests

unit tests jobs use tempest version released in pypi
which has use of mock but in recent changed mock requirement
is removed from requirements file and it end up failing.

- https://zuul.opendev.org/t/openstack/build/c3a33c501c054db9b1eecedb7d4b2c48

Let's add mock into the requirement file to be installed for unit tests
job until we bump the min version of tempest to latest.

2. Nova policy granular work
https://review.opendev.org/#/q/topic:bp/policy-defaults-refresh-deprecated-apis+(status:open+OR+status:merged)
Adding new flag to handle the policy changed in Victoria.

Depends-On: https://review.opendev.org/#/c/745158/

Change-Id: I3683cca390b44146c217ce8600f63a9894057058
diff --git a/releasenotes/notes/changed-nova-policies-victoria-7a5f123238b099d9.yaml b/releasenotes/notes/changed-nova-policies-victoria-7a5f123238b099d9.yaml
new file mode 100644
index 0000000..8540fe7
--- /dev/null
+++ b/releasenotes/notes/changed-nova-policies-victoria-7a5f123238b099d9.yaml
@@ -0,0 +1,13 @@
+---
+features:
+  - |
+    A new policy feature flag called
+    ``[policy_feature_flag].changed_nova_policies_victoria`` has been added to
+    Patrole's config to handle Nova policies changed in Victoria. The policy
+    feature flag is applied to tests that use policies changed in Victoria,
+    including the following:
+
+      - os_compute_api:os-hosts
+      - os_compute_api:os-tenant-networks
+      - os_compute_api:os-volumes
+      - os_compute_api:os-security-groups