[Puppet OpenStack] Fix some bugs in the last train release

The previous release commit set the wrong has about puppet-nova and
released 15.8.0 based on the exactly same hash as 15.7.0. Also,
puppet-murano had 15.4.1 in its metadata.json while released version
was 15.5.0.

Change-Id: I849c42a92c4ccd9b10c3693e38f845b5aea00237

deliverables/train/puppet-murano.yaml

@@ -26,6 +26,10 @@ releases:
     projects:
       - repo: openstack/puppet-murano
         hash: 7a3a8d7e58dfa64b490ce71791262f4403545693
+  - version: 15.5.1
+    projects:
+      - repo: openstack/puppet-murano
+        hash: 6f29cf4e77d96fba764493903da8f3d01937d4ea
 branches:
   - name: stable/train
     location: 15.4.0