Release apertis-update-manager version 0.2020.26

Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>

debian/changelog

+apertis-update-manager (0.2020.26) apertis; urgency=medium
+
+  [ Gireesh Hiremath ]
+  * close the loop device after the offline update
+  * Add AUM upgrade error property
+
+  [ Moses Christopher ]
+  * managerd: adjust log level for failed backend selections
+
+ -- Frédéric Danis <frederic.danis@collabora.com>  Fri, 15 Oct 2021 10:53:09 +0200
+
 apertis-update-manager (0.2020.25) apertis; urgency=medium
 
   [ Gireesh Hiremath ]