[heat] Transition Zed to Unmaintained

This branch reached the end of its official stable maintained period,
hence this patch transition stable/zed branch to Unmaintained. (For
details about Unmaintained state please see: [1][2])

The transitions is as follows:
- tip of the stable/zed branch is tagged with zed-eom tag
- unmaintained/zed branch will be cut from zed-eom tag
- stable/zed branch will be deleted

Note:
- there will no longer be official releases off of zed branch after this
  transition
- backports can be pushed to unmaintained/yoga branch
- openstack-unmaintained-core (or <project>-unmaintained-core groups if
  such exists) have the rights to merge patches

Important: please +1 if the team is ready for us to proceed with this
transition, or -1 if there are any final Zed stable release with
backports currently in flight that we should wait for. For the latter
case, please propose a final Zed stable release patch, and rebase this
patch on top of that, with the latest commit hash of stable/zed.

The transition deadline is May 2nd, 2024. [3]

[1] https://docs.openstack.org/project-team-guide/stable-branches.html#unmaintained
[2] https://governance.openstack.org/tc/resolutions/20230724-unmaintained-branches.html
[3] https://releases.openstack.org

Change-Id: I4548f53b23060e2a65e8b359170a3a1db39af37f

deliverables/zed/heat-agents.yaml

@@ -16,7 +16,13 @@ releases:
       - repo: openstack/heat-agents
         hash: 2e16aa4e57d0995617cfc0872cc3882430a37e56
     diff-start: 4.0.0
+  - version: zed-eom
+    projects:
+      - repo: openstack/heat-agents
+        hash: a71dbdc6e4b69c7ec122fbfb4df66cd657593194
 branches:
   - name: stable/zed
     location: 5.0.0.0rc1
+  - name: unmaintained/zed
+    location: zed-eom
 release-notes: https://docs.openstack.org/releasenotes/heat-agents/zed.html

deliverables/zed/heat-dashboard.yaml

@@ -15,7 +15,13 @@ releases:
       - repo: openstack/heat-dashboard
         hash: 126c5e958b331afbdb2546ef597e3b8baca249e5
     diff-start: 7.0.0
+  - version: zed-eom
+    projects:
+      - repo: openstack/heat-dashboard
+        hash: 5d1ef0faf10c77490051984e850ce0431054db7f
 branches:
   - name: stable/zed
     location: 8.0.0.0rc1
+  - name: unmaintained/zed
+    location: zed-eom
 release-notes: https://docs.openstack.org/releasenotes/heat-dashboard/zed.html

deliverables/zed/heat.yaml

@@ -29,7 +29,13 @@ releases:
     projects:
       - repo: openstack/heat
         hash: d3948706a3ff28d0160157f76f1e18244a8dad5c
+  - version: zed-eom
+    projects:
+      - repo: openstack/heat
+        hash: d3948706a3ff28d0160157f76f1e18244a8dad5c
 branches:
   - name: stable/zed
     location: 19.0.0.0rc1
+  - name: unmaintained/zed
+    location: zed-eom
 release-notes: https://docs.openstack.org/releasenotes/heat/zed.html

deliverables/zed/python-heatclient.yaml

@@ -15,7 +15,13 @@ releases:
     projects:
       - repo: openstack/python-heatclient
         hash: 4935c9003802ac17049278c8c4fb250913972503
+  - version: zed-eom
+    projects:
+      - repo: openstack/python-heatclient
+        hash: b97be45113e82f2be97c31b9c0f96ee1a366926d
 branches:
   - name: stable/zed
     location: 3.1.0
+  - name: unmaintained/zed
+    location: zed-eom
 release-notes: https://docs.openstack.org/releasenotes/python-heatclient/zed.html