Fix: Use api_bp.db_manager instead of undefined db_manager variable

mbetterclient/web_dashboard/routes.py

@@ -4017,7 +4017,7 @@ def get_fixtures():
                 fixture_venue_date = None
                 is_today = False
                 is_past = False
-                if first_match.start_time and db_manager:
+                if first_match.start_time and api_bp.db_manager:
                     venue_start_time = utc_to_venue_datetime(first_match.start_time, api_bp.db_manager)
                     fixture_venue_date = venue_start_time.date()
                     is_today = (fixture_venue_date == today)