update PurchaseAdmin

tournaments/admin.py

@@ -419,6 +419,7 @@ class PurchaseAdmin(SyncedObjectAdmin):
     list_display = ['id', 'user', 'product_id', 'quantity', 'purchase_date', 'revocation_date', 'expiration_date']
     list_filter = ['user']
     ordering = ['-purchase_date']
+    raw_id_fields = ['user']
 
 class CourtAdmin(SyncedObjectAdmin):
     list_display = ['index', 'name', 'club']