Add apertis-update-manager to ostree images

Signed-off-by: Frédéric Dalleau <frederic.dalleau@collabora.com>

apertis-ostree-commit.yaml

@@ -40,6 +40,11 @@ actions:
       # as soon as merged "/usr" will be introduced
       - ostree
 
+  - action: apt
+    description: "OStree update manager"
+    packages:
+      - apertis-update-manager
+
   - action: run
     description: "Save installed package status"
     chroot: false