remove unused synced col from device_files

lib/db/device_files_db.dart

@@ -319,8 +319,11 @@ extension DeviceFiles on FilesDB {
             orElse: () => null,
           );
           if (deviceCollection.thumbnail == null) {
+            //todo: find another image which is already imported in db for
+            // this collection
             _logger.warning(
-                'Failed to find coverThum for ${deviceCollection.name}');
+              'Failed to find coverThumbnail for ${deviceCollection.name}',
+            );
             continue;
           }
         } else {

lib/db/files_db.dart

@@ -305,7 +305,6 @@ class FilesDB {
         CREATE TABLE IF NOT EXISTS device_files (
           id TEXT NOT NULL,
           path_id TEXT NOT NULL,
-          synced INTEGER NOT NULL DEFAULT 0,
           UNIQUE(id, path_id)
        );
        ''',