Allow for Zero amount bills

Sometime you just want to track that you have paid, but you don’t want to mess with the amounts as it might overlap. Specially, it is helpful for the credit card payment saying that I need to pay this credit card on this date and market as paid as soon as I do it. If I enter whatever amount I have paid will overlap the total budgeted amount because sometimes the subscriptions and bills are from that credit card so I’ll be registering it multiple times if I put the amount of credit card payment as well so if I get the option to pay the credit card zero dollar I can still use the app with it all functionality and track the payment.