River Phoenix has been remembered as a “most beautiful one” by his sister on what would have been his 54th birthday. The ‘Stand by Me’ actor died in 1993 from a drug overdose at the age of 23 and his sibling Rain Phoenix, 51, has now shared a string of photos of the actor on her Instagram in his memory. Her photo carousel included a number of quotes attributed to River, and she simply captioned it: “Happy Birthday River.” Red Hot Chili Peppers bassist Flea, 61, who was friends with River and there when the actor collapsed outside the Los Angeles nightclub The Viper Room before his death and ac…