I wouldn't use it. Citrus oils can be very irritating and are not considered safe to use directly even on human skin. I learned something today, because I thought Earl Grey was made with the Bergamot plant, Monarda didyma, aka Bee Balm. I wouldn't use that, either; it has herbal oils used in mouthwash and would probably also be irritating to delicate amphibian skin. Personally I would delay the bath for the brief time it takes to buy plain tea; a tea bath with irritant oils would defeat the purpose.