[mistral] Release for Antelope-2

MAJOR vesion bumps in:
* python-mistralclient: due to dropping py36 & py37 support
* mistral-extra: due to dropping bay and baymodel support

Change-Id: Ie323726a13173d1347fa0056381caf67364a8936

deliverables/antelope/mistral-extra.yaml

@@ -6,3 +6,8 @@ team: mistral
 type: library
 repository-settings:
   openstack/mistral-extra: {}
+releases:
+  - version: 13.0.0
+    projects:
+      - repo: openstack/mistral-extra
+        hash: e0687d607319b796503859353b8f3ab1cc9aa9f5

deliverables/antelope/mistral-lib.yaml

@@ -6,3 +6,8 @@ team: mistral
 type: library
 repository-settings:
   openstack/mistral-lib: {}
+releases:
+  - version: 2.8.0
+    projects:
+      - repo: openstack/mistral-lib
+        hash: 7bbfa4f945a68738dcdae26e5c4f2f4f4a657429

deliverables/antelope/python-mistralclient.yaml

@@ -6,3 +6,8 @@ launchpad: python-mistralclient
 release-model: cycle-with-intermediary
 repository-settings:
   openstack/python-mistralclient: {}
+releases:
+  - version: 5.0.0
+    projects:
+      - repo: openstack/python-mistralclient
+        hash: b94abb44d9d0f92a527dfa1ecf2e4d3c1be6178c