Mark requirements newton branch as EOL

This seems to be missing for requirements and the branch is still
visible at opendev [1]. (However 'git checkout stable/newton' gives
some error for me locally). Let's try to clean up this branch.

[1] https://opendev.org/openstack/requirements/commits/branch/stable/newton

Change-Id: Id7a52ccc244e52546d279dfac80b19ed0d68ef89

deliverables/newton/requirements.yaml

@@ -7,6 +7,11 @@ release-model: cycle-with-intermediary
 stable-branch-type: tagless
 repository-settings:
   openstack/requirements: {}
+releases:
+  - projects:
+      - hash: d94785ceb702587131ce98a1b9f05b2869a66180
+        repo: openstack/requirements
+    version: newton-eol
 branches:
   - location:
       openstack/requirements: c589637b184e77901d37cc7faa93dbb906979448