add step param for groupstage

tournaments/models/group_stage.py

@@ -13,6 +13,7 @@ class GroupStage(models.Model):
     format = models.IntegerField(default=FederalMatchCategory.NINE_GAMES, choices=FederalMatchCategory.choices, null=True, blank=True)
     start_date = models.DateTimeField(null=True, blank=True)
     name = models.CharField(max_length=200, null=True, blank=True)
+    step = models.IntegerField(default=0)
 
     def __str__(self):
         return self.display_name()