PARIS/BEIJING (Reuters) - Vivendi (VIV.PA) is in talks to sell up to 20% of Universal Music Group (UMG) to Tencent (0700.HK), valuing its prized asset at around 30 billion euros ($34 billion), in an attempt to break into China’s growing but tightly-controlled music market. Lady Gaga arrives at the Metropolitan Museum of Art Costume Institute…