linux/appimage: remove "universe" and "backports" repos

We don't need packages from these repositories.

appimage/AppImageBuilder.yml

@@ -42,10 +42,9 @@ AppDir:
   apt:
     arch: amd64
     sources:
-      - sourceline: deb http://archive.ubuntu.com/ubuntu/ jammy main universe
-      - sourceline: deb http://archive.ubuntu.com/ubuntu/ jammy-updates main universe
-      - sourceline: deb http://archive.ubuntu.com/ubuntu/ jammy-backports main universe
-      - sourceline: deb http://archive.ubuntu.com/ubuntu/ jammy-security main universe
+      - sourceline: deb http://archive.ubuntu.com/ubuntu/ jammy main
+      - sourceline: deb http://archive.ubuntu.com/ubuntu/ jammy-updates main
+      - sourceline: deb http://archive.ubuntu.com/ubuntu/ jammy-security main
         key_url: http://keyserver.ubuntu.com/pks/lookup?op=get&search=0x871920D1991BC93C
 
     include: