Fix age calculation to use tournament start date

tournaments/models/tournament.py

@@ -1420,11 +1420,11 @@ class Tournament(BaseModel):
         if birth_year is None:
             return reasons if reasons else None
 
-        current_year = timezone.now().year
-        if timezone.now().month >= 9:  # Check if current month is September or later
-            current_year += 1
+        tournament_start_year = self.start_date.year
+        if self.start_date.month >= 9:  # Check if tournament start month is September or later
+            tournament_start_year += 1
 
-        user_age = current_year - int(birth_year)
+        user_age = tournament_start_year - int(birth_year)
         # Check age category restrictions
 
         if self.federal_age_category == FederalAgeCategory.A11_12 and user_age > 12: