My Apartment just added parking rules mid lease stating only 2 cars allowed

Location: houston texas

past 2 years I've been living here no problem with my 3 cars. Now they are saying we need to start registering our cars in their new parking system and they will only issue 1 car per adult. If I want to keep my 3rd car I need to rent a garage at 100$ a month. I checked my lease agreement no where it says anything about parking and they are threatening to tow my car....