[WarpPay] Changed Pincode to nullable

www/web/warppay/models.py

@@ -56,7 +56,7 @@ class UserCredit(models.Model):
     uid = models.CharField(max_length=100,unique=True)
     card_id = models.CharField(max_length=10, null=True) # Unique only with django 1.11
     credit = models.FloatField()
-    pinCode = models.CharField(max_length=100)
+    pinCode = models.CharField(max_length=100, null=True)
 
     def __str__(self):
         return self.uid