Today (April 23) marks Louis’ sixth birthday, and sticking to tradition, Kate Middleton and Prince William have shared an adorable new photo of their youngest. Every year, on her children’s birthdays, Kate Middleton takes and posts a new picture to celebrate the occasion. However, due to her recent cancer diagnosis and Photoshop fiasco, doubts were raised on whether she’d partake in the tradition this year. But she’s not letting anything stop her as she and Prince William share the adorable photo of Prince Louis on social media. Kate Middleton releases new picture of Prince Louis to celebrate …