Release magnum-ui for stable/train

This release picks up new commits to magnum-ui since
the last release from stable/train.

This is being proposed as a convenience to help make sure stable
changes are being released. If the team is good with this going out,
please respond with a +1 to let the release team know it is OK to
proceed.

If it is not wanted at this time, or if there are more changes that
would be good to get merged before doing a  stable release, please
leave a -1 with a comment with what the team would prefer. We can
then either abandon this patch, or wait for an update with a new
commit hash to use instead.

Signed-off-by: Elod Illes <elod.illes@est.tech>
Change-Id: Ibb92a709dfaf17e2f45d5b730862e557390e74ec

deliverables/train/magnum-ui.yaml

@@ -18,6 +18,10 @@ releases:
     projects:
       - repo: openstack/magnum-ui
         hash: 2fd052efa8a5a7ec6669c6e13622213fc43f5721
+  - version: 5.3.1
+    projects:
+      - repo: openstack/magnum-ui
+        hash: 7e10a6aec2adb7c6ec740f873c616522a0ee7be5
 branches:
   - name: stable/train
     location: 5.2.0