ttrss: Include dbconfig configuration file in backup

- This will ensure that dbconfig is every triggered and regenerates the
configuration/setup, everything is consistent.

Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

plinth/modules/ttrss/manifest.py

@@ -54,7 +54,10 @@ backup = {
         'files': ['/var/lib/plinth/backups-data/ttrss-database.sql']
     },
     'secrets': {
-        'files': ['/etc/tt-rss/database.php']
+        'files': [
+            '/etc/tt-rss/database.php',
+            '/etc/dbconfig-common/tt-rss.conf',
+        ]
     },
     'services': ['tt-rss']
 }