Replace concat() with || due to sqlite3 limitation

app/queries/monthly_stats.py

@@ -29,7 +29,7 @@ def get_all_monthly_analytics(end_date:str = 'now'):
                 group by counter_id, strftime('%m', timestamp),  strftime('%Y', timestamp)
             )
             select 
-                concat(m.m,', ',m.y) as "month",
+                m.m || ', ' || m.y as "month",
                 case 
                     when counter_id is null then json_object()
                     else json_group_object(name, count)
@@ -69,7 +69,7 @@ def get_monthly_analytics(counter_id:int, end_date:str = 'now'):
                 group by strftime('%m', timestamp),  strftime('%Y', timestamp)
             )
             SELECT 
-                concat(m.m,', ',m.y) as "month",
+                m.m || ', ' || m.y as "month",
                 coalesce(s.count, 0) as count 
             FROM months as m
             LEFT JOIN stats as s on s.m = m.m and s.y = m.y