cluster-backup. Preserve list order

Items returned by Redis lists are randomly sorted. Ensure the same items
order is dumped to backup to avoid generating different versions of the
dump for the same data.

core/imageroot/var/lib/nethserver/cluster/bin/cluster-backup

@@ -76,7 +76,7 @@ for k in ['network', 'ui_name', 'uuid']:
     dump['cluster'][k] = rdb.get(f'cluster/{k}') or ''
 
 # cluster: favorite apps
-dump['cluster']['favorites'] = list(rdb.smembers(f'cluster/favorites'))
+dump['cluster']['favorites'] = sorted(rdb.smembers(f'cluster/favorites'))
 
 # cluster: module URL override
 dump['cluster']['override']['modules'] = rdb.hgetall('cluster/override/modules')
@@ -86,7 +86,7 @@ for m in rdb.scan_iter('module/*/backups'):
     k = m.removeprefix('module/').removesuffix('/backups')
     uuid = rdb.hget(f'module/{k}/environment', 'MODULE_UUID')
     dump['modules'][uuid] = {'backups': []}
-    dump['modules'][uuid]['backups'] = list(rdb.smembers(m))
+    dump['modules'][uuid]['backups'] = sorted(rdb.smembers(m))
 
 # nodes: vpn, label
 for v in rdb.scan_iter('node/*/vpn'):