Selena Gomez posted a sweet birthday tribute to her longtime friend, Francia Raísa, on Instagram on Wednesday. Raísa and Gomez have been friends for nearly 15 years, and Raisa donated her kidney to Gomez -- who needed a transplant due to her battle with lupus in Sept. 2017. Last year, however, the pair had a public falling out when Gomez did not name Raísa as a ‘friend in the industry’ in an interview with ‘Rolling Stone.’